// #include<iostream> //romeo: added
#include<fstream> //romeo: added
#include<vector>
#include<cstdio>
#include<algorithm>
#include<cassert> //romeo: added
#define MAX 10001
#define edge pair<int,int>
using namespace std;
vector< pair<int, edge > > Graph,MST;
int n,e,parent[MAX];
void initialize(int n)
{
    for(int i=1; i<=n; i++)
    {
        parent[i] = i;
    }
    MST.clear();
    Graph.clear();
}
int findSet(int x, int *parent)
{
    if(x!=parent[x])
    {
        parent[x] = findSet(parent[x],parent);
    }
    return parent[x];
}
void albero_minimo()
{
    ofstream fout("output.txt"); assert( fout ); //romeo: added
    sort(Graph.begin(),Graph.end());
    int total = 0;
    for(int i=0; i<e; i++)
    {
        int pu = findSet(Graph[i].second.first,parent);
        int pv = findSet(Graph[i].second.second,parent);
        if(pu!=pv)
        {
            total+=Graph[i].first;
            MST.push_back(Graph[i]);
            parent[pu] = parent[pv];
        }
    }
    fout << total << "\n";   //romeo: cin --> fin
    for(int i=0; i < n-1; i++)  //romeo: added from your writing
      fout << MST[i].second.first << " " << MST[i].second.second << endl;  //romeo: added from your writing
    fout.close(); //romeo: added
}
int main()
{
    ifstream fin("input.txt"); assert( fin ); //romeo: added
    fin>>n>>e;   //romeo: cin --> fin
    initialize(n);
    int u,v,w;
    for(int i=0; i<e; i++)
    {
        fin>>u>>v>>w;   //romeo: cin --> fin
        Graph.push_back(pair<int, edge>(w,edge(u,v)));
    }
    fin.close(); //romeo: added

    albero_minimo();
    
    return 0;
}