#include <bits/stdc++.h>
using namespace std;

vector <int> t;
int _find (int x) {
    if (t[x]==x)
        return x;
    return t[x]=_find(t[x]);
}

void _union (int x, int y) {
    int p1=t[x],
        p2=t[y];
    t[p2]=p1;
}

int main () {
    ifstream fin ("apm.in");
    ofstream fout ("apm.out");
    int n, m, i, j, c, k;
    fin >> n >> m;
    vector <tuple <int, int, int>> muchii;
    for (k=0; k<m; k++) {
        fin >> i >> j >> c;
        muchii.push_back(make_tuple(i, j, c));
    }
    fin.close();

    sort (muchii.begin(), muchii.end(), [] (const tuple <int, int, int> &a, const tuple <int, int, int> &b) -> bool {
                                            return (get<2>(a))<(get<2>(b));
                                        });
    t.assign(n+1, 0);
    iota(t.begin(), t.end(), 0);

    fout << "                \n" //wtf
         << n-1 << '\n';
    int s=0, ct=0;
    auto it=muchii.begin();
    while (it!=muchii.end() && ct<n) {
        if (_find(get<0>(*it)) != _find(get<1>(*it))) {
            _union(get<0>(*it), get<1>(*it));
            s+=get<2>(*it);
            ct++;
            fout << get<0>(*it) << ' ' << get<1>(*it) << '\n';
        }
        ++it;
    }

    fout.seekp(0);
    fout << s;
    fout.close();
    return 0;
}