#include <iostream>
#include <fstream>
#include <queue>
#include <vector>
#include <stack>
#include <bits/stdc++.h>
using namespace std;

bool compara(int const a, int const b)
{
    return (a > b);
}

class Graf
{
   protected:
       int numarNoduri, numarMuchii;
       vector <vector <int>> listaAdiacenta;
   public:
       Graf(int const, int const, vector <vector<int>>);
       Graf(const Graf &graf);
       ~Graf();
       int get_noduri() const;
       int get_muchii() const;
       vector <vector<int>> get_lista() const;
       void afisare(ostream&);
       friend ostream& operator<<(ostream& out, Graf &g);
       vector <int> BFS(int);
       int DFS_componente_conexe();
       vector <int> sortareTopologica(int []);
       int existaGrafHH(vector <int> &, int);
       void ctc(vector <int>, stack <int>, vector <vector<int>>, vector <int>, ostream &);
       void DfsMuchiiCritice(int, int, vector <int> &, vector <int> &, vector <int> &, vector <vector<int>> &, ostream &);
       int Find(int, vector <int> &);
       void Union(int, int, vector <int> &, vector <int> &);
    private:
       void DFS(int, vector <int> &);
       void dfs1(int, vector <int> &, stack <int>&);
       void dfs2(int, vector <int> &, vector <vector<int>>, vector <vector<int>> &, vector <int> &);
};

Graf :: Graf(int const numarNodurioduri, int const numarMuchiiuchii, vector <vector<int>> lista)
{
     numarNoduri = numarNodurioduri;
     numarMuchii = numarMuchiiuchii;
     listaAdiacenta = lista;
}

Graf :: Graf(const Graf & graf)
{
     numarNoduri = graf.numarNoduri;
     numarMuchii = graf.numarMuchii;
     listaAdiacenta = graf.listaAdiacenta;
}

Graf :: ~Graf()
{
    numarNoduri = 0;
    numarMuchii = 0;
    listaAdiacenta.clear();
}

int Graf :: get_noduri() const
{
    return numarNoduri;
}

int Graf :: get_muchii() const
{
    return numarMuchii;
}

vector <vector<int>> Graf :: get_lista() const
{
    return listaAdiacenta;
}

void Graf :: afisare(ostream &out)
{
    out << "Numar de noduri: " << numarNoduri << "\n";
    out << "Numar de muchii: " << numarMuchii << "\n";
    for (int i = 0; i < numarNoduri; i++)
        for (int j = 0; j < listaAdiacenta[i].size(); j++)
           {
               out << "Muchia "  << i << " " << listaAdiacenta[i][j];
               out << "\n";
           }
}

ostream& operator<<(ostream& out, Graf &g)
{
    g.afisare(out);
    return out;
}

vector <int> Graf :: BFS(int start)
{
    vector <int> cost(numarNoduri + 1, -1);
    int S;
    queue <int> coada;
    coada.push(start);
    cost[start] = 0;
    while (!coada.empty())
    {
        S = coada.front();
        for (int i = 0; i < listaAdiacenta[S].size(); i++)
        {
            int nod_curent = listaAdiacenta[S][i];
            if (cost[nod_curent] == -1)
            {
                cost[nod_curent] = cost[S] + 1;
                coada.push(nod_curent);
            }
        }
        coada.pop();
    }
    return cost;
}


void Graf :: DFS(int nod, vector <int> &viz)
{
    viz[nod] = 1;
    for (int i = 0; i < listaAdiacenta[nod].size(); i++)
    {
        int nod_curent = listaAdiacenta[nod][i];
        if (viz[nod_curent] == 0)
            DFS(nod_curent, viz);
    }
}

int Graf :: DFS_componente_conexe()
{
    vector <int> viz(numarNoduri + 1, 0);
    int nrCC = 0;
    for (int i = 1; i <= numarNoduri; i++)
    {
        if (viz[i] == 0)
        {
            DFS(i, viz);
            nrCC ++;
        }
    }
    return nrCC;
}

vector <int> Graf :: sortareTopologica(int grade[])
{
    queue <int> coada;
    vector <int> rez;
    for (int i = 1; i <= numarNoduri; i++)
        if (grade[i] == 0)
            coada.push(i);
    while (!coada.empty())
    {
        int nod_curent = coada.front();
        rez.push_back(nod_curent);
        coada.pop();
        for (int i = 0; i < listaAdiacenta[nod_curent].size(); i++)
        {
            int vecin = listaAdiacenta[nod_curent][i];
            grade[vecin]--;
            if (grade[vecin] == 0)
                coada.push(vecin);
        }
    }
    return rez;
}

int Graf :: existaGrafHH(vector <int> &v, int n)
{
    int ok = 1;
    while (ok == 1)
    {
        sort(v.begin(), v.end(), compara);
        if (v[0] == 0)
            break;
        int nr = v[0];
        v.erase(v.begin());
        if (nr > v.size())
         {
            ok = 0;
            break;
         }
        for (int i = 0; i < nr; i++)
        {
            v[i] = v[i] - 1;
            if (v[i] < 0)
                {
                    ok = 0;
                    break;
                }
        }
    }
    if (ok == 1) return 1;
    return 0;
}

void Graf :: dfs1(int nod, vector <int> &vizitat, stack <int> &stiva)
{
    vizitat[nod] = 1;
    for (int i = 0; i < listaAdiacenta[nod].size(); i++)
    {
        int nod_curent = listaAdiacenta[nod][i];
        if (vizitat[nod_curent] == 0)
            dfs1(nod_curent, vizitat, stiva);
    }
   stiva.push(nod);
}

void Graf :: dfs2(int nod, vector <int> &vizitatTr, vector <vector<int>> listaTr, vector <vector<int>> &rez, vector <int> &vector_aux)
{
    vector_aux.push_back(nod);
    vizitatTr[nod] = 1;
    for (int i = 0; i < listaTr[nod].size(); i++)
    {
        int nod_curent = listaTr[nod][i];
        if (vizitatTr[nod_curent] == 0)
            dfs2(nod_curent, vizitatTr, listaTr, rez, vector_aux);
    }
}

void Graf :: ctc(vector <int> vizitat, stack <int> stiva, vector <vector<int>> listaTr, vector <int> vizitatTr, ostream &out)
{
    vector <vector<int>> rez(numarNoduri + 1);
    int nr = 0;
    for (int i = 1; i <= numarNoduri; i++)
        if (vizitat[i] == 0)
            dfs1(i, vizitat, stiva);
    while (!stiva.empty())
    {
       int v = stiva.top();
       stiva.pop();
       if (vizitatTr[v] == 0)
       {
          vector <int> vector_aux;
          dfs2(v, vizitatTr, listaTr, rez, vector_aux);
          rez.push_back(vector_aux);
          nr++;
       }
    }
    out << nr << "\n";
    for (int i = 0; i < rez.size(); i++)
    {
       if (rez[i].size() != 0)
        {
           for (int j = 0; j < rez[i].size(); j++)
              out << rez[i][j] << " ";
           out << "\n";
        }
    }
}

void Graf :: DfsMuchiiCritice(int nod, int tata, vector <int> &vizitat, vector <int> &nivel, vector <int> &nivelInt, vector <vector<int>> &listaAdiacenta,
                              ostream &out)
{
    vizitat[nod] = 1;
    nivel[nod] = nivel[tata] + 1;
    nivelInt[nod] = nivel[nod];
    for (int i = 0; i < listaAdiacenta[nod].size(); i++)
    {
        int copil = listaAdiacenta[nod][i];
        if (copil != tata)
        {
            if (vizitat[copil] == 1)
                {
                    if (nivelInt[nod] > nivel[copil])
                       nivelInt[nod] = nivel[copil];
                }
            else
            {
                DfsMuchiiCritice(copil, nod, vizitat, nivel, nivelInt, listaAdiacenta, out);
                if (nivelInt[nod] > nivelInt[copil])
                    nivelInt[nod] = nivelInt[copil];
                if (nivel[nod] < nivelInt[copil])
                    out << nod << " " << copil << "\n";
            }
        }
    }
}

int Graf :: Find(int nod, vector <int> &tata)
{
    if (tata[nod] == nod)
          return nod;
    int rez = Find(tata[nod], tata);
    tata[nod] = rez;
    return rez;
}

void Graf :: Union(int nod1, int nod2, vector <int> &tata, vector <int> &rang)
{
    int TataNod1 = Find(nod1, tata);
    int TataNod2 = Find(nod2, tata);
    if (TataNod1 == TataNod2)
        return;
    if (rang[TataNod1] < rang[TataNod2])
           tata[TataNod1] = TataNod2;
    else if (rang[TataNod1] > rang[TataNod2])
             tata[TataNod2] = TataNod1;
         else
         {
            tata[TataNod2] = TataNod1;
            rang[TataNod1]++;
         }
}

bool comparaCost (vector <int> v1, vector <int> v2)
{
    return v1[2] < v2[2];
}

class GrafPonderat : public Graf
{
    private:
        vector <vector <pair<int, int>>> muchiiCuCost;
        int find_tata(int, vector <int>);
        void set_tata(int, int, vector <int> &);
    public:
        GrafPonderat(int, int, vector <vector <int>>, vector <vector<pair <int, int>>>);
        vector <pair<int, int>> apmKruskal(ostream &, vector <int>, vector <vector <int>>);
        vector <int> dijkstra();
        void bellmanford(ostream &);
};

GrafPonderat :: GrafPonderat(int numarNodurioduri, int numarMuchiiuchii, vector <vector <int>> lista, vector <vector<pair<int, int>>> muchiiCost) : Graf(numarNodurioduri, numarMuchiiuchii, lista) ///apelam constructorul din baza
{
    muchiiCuCost = muchiiCost;
}

int GrafPonderat :: find_tata(int nod, vector <int> tata)
{
    while (nod != tata[nod])
        nod = tata[nod];
    return nod;
}

void GrafPonderat :: set_tata(int nod1, int nod2, vector <int> &tata)
{
    tata[nod1] = tata[nod2];
}

vector <pair<int, int>> GrafPonderat :: apmKruskal(ostream &out, vector <int> tata, vector <vector <int>> muchiiCost)
{
    vector <pair<int, int>> rez;
    sort (muchiiCost.begin(), muchiiCost.end(), comparaCost);
    int cost_total = 0, nod1, nod2, tata1, tata2, numarMuchiiuchiiAPM = 0, index_muchie = 0;
    while (numarMuchiiuchiiAPM < numarNoduri - 1)
    {
        nod1 = muchiiCost[index_muchie][0];
        nod2 = muchiiCost[index_muchie][1];
        tata1 = find_tata(nod1, tata);
        tata2 = find_tata(nod2, tata);
        if (tata1 != tata2)
        {
            if (tata1 < tata2)
                set_tata(tata1, tata2, tata);
            else
                set_tata(tata2, tata1, tata);
            rez.push_back(make_pair(nod1, nod2));
            cost_total = cost_total + muchiiCost[index_muchie][2];
            numarMuchiiuchiiAPM++;
        }
        index_muchie++;
    }
    out << cost_total << "\n";
    out << numarMuchiiuchiiAPM << "\n";
    return rez;
}

vector <int> GrafPonderat :: dijkstra()
{
    vector <int> distante(numarNoduri + 1, INT_MAX);
    vector <int> inCoada(numarNoduri + 1, 0);
    priority_queue <pair <int, int>, vector <pair <int, int>>, greater<pair <int, int>>> coada;
    distante[1] = 0;
    coada.push({0, 1});
    inCoada[1] = 1;
    while (!coada.empty())
    {
        int nodCurent = coada.top().second;
        coada.pop();
        inCoada[nodCurent] = 0;
        for (int i = 0; i < muchiiCuCost[nodCurent].size(); i++)
        {
            int vecin, cost_vecin;
            vecin = muchiiCuCost[nodCurent][i].first;
            cost_vecin = muchiiCuCost[nodCurent][i].second;
            if (distante[nodCurent] + cost_vecin < distante[vecin])
            {
                distante[vecin] = distante[nodCurent] + cost_vecin;
                if (inCoada[vecin] == 0)
                {
                    coada.push({distante[vecin], vecin});
                    inCoada[vecin] = 1;
                }
            }
        }
    }
    return distante;
}

void GrafPonderat :: bellmanford(ostream &out)
{
    vector <int> distante(numarNoduri + 1, INT_MAX);
    vector <int> inCoada(numarNoduri + 1, 0);
    vector <int> vizitat(numarNoduri + 1, 0);
    priority_queue <pair <int, int>, vector <pair <int, int>>, greater<pair <int, int>>> coada;
    int ok = 1;
    distante[1] = 0;
    coada.push({0, 1});
    inCoada[1] = 1;
    while (!coada.empty())
    {
        int nodCurent = coada.top().second;
        coada.pop();
        inCoada[nodCurent] = 0;
        vizitat[nodCurent]++;
        if (vizitat[nodCurent] > numarNoduri - 1)
        {
             ok = 0;
             break;
        }
        for (int i = 0; i < muchiiCuCost[nodCurent].size(); i++)
        {
            int vecin, cost_vecin;
            vecin = muchiiCuCost[nodCurent][i].first;
            cost_vecin = muchiiCuCost[nodCurent][i].second;
            if (distante[nodCurent] + cost_vecin < distante[vecin])
            {
                distante[vecin] = distante[nodCurent] + cost_vecin;
                if (inCoada[vecin] == 0)
                {
                    coada.push({distante[vecin], vecin});
                    inCoada[vecin] = 1;
                }
            }
        }
    }
    if (ok == 0)
        out << "Ciclu negativ!";
    else
        for (int i = 2; i < distante.size(); i++)
            out << distante[i] << " ";
}

void problemaBFS()
{
    int n, s, st, dr, m;
    ifstream fin("bfs.in");
    ofstream fout("bfs.out");
    fin >> n >> m >> s;
    vector <vector<int>> listaAdiacenta(n + 1);
    for (int i = 1; i <= m; i++)
    {
       // cin >> st >> dr;
        fin >> st >> dr;
        listaAdiacenta[st].push_back(dr);
    }
    Graf g(n, m, listaAdiacenta);
    vector <int> cost = g.BFS(s);
    for (int i = 1; i <= n; i++)
        fout << cost[i] << " ";
    fin.close();
    fout.close();
}

void problemaDFS()
{
    int n, m, st, dr;
    ifstream fin("dfs.in");
    ofstream fout("dfs.out");
    fin >> n >> m;
    vector <vector<int>> listaAdiacenta(n + 1);
    for (int i = 1; i <= m; i++)
    {
       // cin >> st >> dr;
        fin >> st >> dr;
        listaAdiacenta[st].push_back(dr);
        listaAdiacenta[dr].push_back(st);
    }
    Graf g(n, m, listaAdiacenta);
    int rez = g.DFS_componente_conexe();
    fout << rez;
    fin.close();
    fout.close();
}

void problemaHavelHakimi()
{
    vector <int> v;
    int n, el;
    cout << "Introduceti numarul de elemente: ";
    cin >> n;
    cout << "Introduceti gradele: ";
    for (int i = 0; i < n; i++)
    {
        cin >> el;
        v.push_back(el);
    }
    vector <vector<int>> vgol = {};
    Graf g(0, 0, vgol);
    int rez = g.existaGrafHH(v, n);
    if (rez == 1)
        cout << "Da, exista graf!";
    else cout << "Nu, nu exista graf!";
}

void problemaSortareTopologica()
{
    int n, m, st, dr, grade[50001] = {0};

    ifstream fin("sortaret.in");
    ofstream fout("sortaret.out");
    fin >> n >> m;
    vector <vector<int>> listaAdiacenta (n + 1);
    for (int i = 1; i <= m; i++)
    {
       // cin >> st >> dr;
        fin >> st >> dr;
        listaAdiacenta[st].push_back(dr);
        grade[dr]++;
    }
    Graf g(n, m, listaAdiacenta);
    vector <int> rez = g.sortareTopologica(grade);
    for (int i=0; i < rez.size(); i++)
        fout << rez[i] << " ";
    fin.close();
    fout.close();
}

void problemaComponenteTareConexe()
{
    int n, m, st, dr;

    ifstream fin("ctc.in");
    ofstream fout("ctc.out");
    fin >> n >> m;
    vector <vector<int>> listaTr(n + 1);
    vector <vector<int>> listaAdiacenta(n + 1);
    vector <int> vizitat(n + 1, 0);
    vector <int> vizitatTr(n + 1, 0);
    stack <int> stiva;
    for (int i = 1; i <= m; i++)
    {
        fin >> st >> dr;
        listaAdiacenta[st].push_back(dr);
        listaTr[dr].push_back(st);
    }
    Graf g(n, m, listaAdiacenta);
    g.ctc(vizitat, stiva, listaTr, vizitatTr, fout);
    fin.close();
    fout.close();
}

void problemaCriticalConnectionsLeetCode()
{
    int n, m, st, dr;
    cout << "Numerotare noduri de la index 0! Graf neorientat!" << "\n";
    cout << "Introduceti numarul de noduri: ";
    cin >> n;
    cout << "Introduceti numarul de muchii: ";
    cin >> m;
    cout << "Introduceti muchiile: ";
    vector <vector<int>> listaAdiacenta(n + 1);
    vector <int> vizitat(n + 1, 0);
    vector <int> nivel(n + 1, 0);
    vector <int>nivelInt(n + 1, 0);
    for (int i = 1; i <= m; i++)
    {
        cin >> st >> dr;
        listaAdiacenta[st].push_back(dr);
        listaAdiacenta[dr].push_back(st);
    }
    Graf g(n, m, listaAdiacenta);
    cout << "Muchii critice: ";
    g.DfsMuchiiCritice(0, 0, vizitat, nivel, nivelInt, listaAdiacenta, cout);
}

void problemaPaduriDeMultimiDisjuncte()
{
    ifstream fin("disjoint.in");
    ofstream fout("disjoint.out");
    int n, m, st, dr, operatie;
    fin >> n >> m;
    vector <vector<int>> vgol = {};
    vector <int> tata(n + 1);
    vector <int> rang(n + 1, 0);
    Graf g(n, m, vgol);
    for (int i = 1; i <= n; i++)
           tata[i] = i;
    for (int i = 1; i <= m; i++)
    {
        fin >> operatie >> st >> dr;
        if (operatie == 1)
        {
            g.Union(st, dr, tata, rang);
        }
        else if (g.Find(st, tata) == g.Find(dr, tata))
                 fout << "DA" << "\n";
             else fout << "NU" << "\n";
    }
    fin.close();
    fout.close();
}


void problemaAPMKruskal()
{
    ifstream fin("apm.in");
    ofstream fout("apm.out");
    int n, m, st, dr, cost;

    fin >> n >> m;
    vector <vector <int>> lista = {};
    vector <vector<pair <int, int>>> muchiiCuCost(n + 1, {{0,0}});
    vector <vector <int>> muchiiCost;
    for (int i = 1; i <= m; i++)
    {
        fin >> st >> dr >> cost;
        muchiiCost.push_back({st, dr, cost});
    }
    GrafPonderat g(n, m, lista, muchiiCuCost);
    vector <int> tata(n + 1);
    for (int i = 1; i <= n; i++)
        tata[i] = i;
    vector <pair<int, int>> rezultat = g.apmKruskal(fout, tata, muchiiCost);
    for (int i = 0; i < rezultat.size(); i++)
       fout << rezultat[i].first << " " << rezultat[i].second << "\n";
    fin.close();
    fout.close();
}

void problemaDijkstra()
{
    ifstream fin("dijkstra.in");
    ofstream fout("dijkstra.out");
    int n, m, st, dr, cost;
    fin >> n >> m;
    vector <vector <int>> lista = {};
    vector <vector<pair <int, int>>> muchiiCuCost(n + 1);
    for (int i = 1; i <= m; i++)
    {
        fin >> st >> dr >> cost;
        muchiiCuCost[st].push_back(make_pair(dr, cost));
    }
    GrafPonderat g(n, m, lista, muchiiCuCost);
    vector <int> rez = g.dijkstra();
    for (int i = 2; i < rez.size(); i++)
        if (rez[i] == INT_MAX)
            fout << 0 << " ";
        else
            fout << rez[i] << " ";
    fin.close();
    fout.close();
}

void problemaBellmanford()
{
    ifstream fin("bellmanford.in");
    ofstream fout("bellmanford.out");
    int n, m, st, dr, cost;
    fin >> n >> m;
    vector <vector <int>> lista = {};
    vector <vector<pair <int, int>>> muchiiCuCost(n + 1);
    for (int i = 1; i <= m; i++)
    {
        fin >> st >> dr >> cost;
        muchiiCuCost[st].push_back(make_pair(dr, cost));
    }
    GrafPonderat g(n, m, lista, muchiiCuCost);
    g.bellmanford(fout);
    fin.close();
    fout.close();
}

int main()
{
    problemaAPMKruskal();
    return 0;
}