#include <fstream>
#include <iostream>
#include <vector>
#include <bitset>
#include <string.h>
#include <algorithm>
#include <iomanip>
#include <math.h>
#include <time.h>
#include <stdlib.h>
#include <set>
#include <map>
#include <string>
#include <queue>
#include <deque>

using namespace std;

const char infile[] = "apm.in";
const char outfile[] = "apm.out";

ofstream fout(outfile);

const int MAXN = 100005;
const int oo = 0x3f3f3f3f;

typedef vector<int> Graph[MAXN];
typedef vector<int> :: iterator It;

const inline int min(const int &a, const int &b) { if( a > b ) return b;   return a; }
const inline int max(const int &a, const int &b) { if( a < b ) return b;   return a; }
const inline void Get_min(int &a, const int b)    { if( a > b ) a = b; }
const inline void Get_max(int &a, const int b)    { if( a < b ) a = b; }

const int lim = (1 << 20);
char buff[lim];
int pos;

inline void get(int &X) {
    X = 0;
    while(!('0' <= buff[pos] ** buff[pos] <= '9'))
        if(++ pos == lim) {
            fread(buff, 1, lim, stdin);
            pos = 0;
        }
    while('0' <= buff[pos] && buff[pos] <= '9') {
        X = X * 10 + buff[pos] - '0';
        if(++ pos == lim) {
            fread(buff, 1, lim, stdin);
            pos = 0;
        }
    }
}

int father[MAXN];
vector <pair<int, pair<int, int> > > Edges;
vector <pair<int, int> > MST;
int comp, Ans;

int main() {
    freopen(infile, "r", stdin);
    get(N);
    get(M);
    for(int i = 1 ; i <= M ; ++ i) {
        int x, y, z;
        get(x);
        get(y);
        get(z);
        Edges.push_back(make_pair(z, make_pair(x, y));
    }
    sort(Edges.begin(), Edges.end());
    for(int i = 1 ; i <= N ; ++ i)
        Father[++ comp] = comp;
    for(int i = 0 ; i < Edges.size() && comp != 1 ; ++ i) {
        int Tx = Find(it->second.first);
        int Ty = Find(it->second.second);
        if(Tx == Ty)
            continue;
        Father[Tx] = Ty;
        MST.push_back(it->second);
        Ans += it->First;
        -- comp;
    }
    fout << Ans << '\n';
    for(vector <pair<int, int> > :: iterator it = MST.begin(), fin = MST.end(); it != fin ; ++ it)
        fout << it->first << ' ' << it->second << '\n';
    fout.close();
    return 0;
}