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

ifstream f("apm.in");
ofstream g("apm.out");

set < pair < int , int > > s;

vector < pair < int , int > > v[200005];
int n,m;
int x,y,c;
int dist[200005];
bool viz[200005];
int t[200005];

int sum=0;

int main()
{
    f >> n >> m;
    for (int i=1;i<=m;i++) {
        f >> x >> y >> c;
        v[x].push_back({y, c});
        v[y].push_back({x, c});
    }

    dist[1] = 0; viz[1] = 1;
    fill(dist+2, dist+n+1, INT_MAX);
    s.insert({0, 1});

    while (!s.empty()) {
        int nod = s.begin()->second;
        int dist_nod = s.begin()->first;
        viz[nod] = 1;
        sum += dist_nod;
        s.erase(s.begin());
        for (auto edge:v[nod]) {
            if (dist[edge.first] > edge.second && !viz[edge.first]) {
                s.erase({dist[edge.first], edge.first});
                dist[edge.first] = edge.second;
                s.insert({dist[edge.first], edge.first});
                t[edge.first] = nod;
            }
        }
    }
    g << sum << '\n';
    g << n-1 << '\n';
    for (int i=1;i<=n;i++) {
        if (t[i]!=0) {
            g << i << " " << t[i] << '\n';
        }
    }
    return 0;
}