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#include <bits/stdc++.h>
#define N 1001
using namespace std;
ifstream fin("kruskal.in");
ofstream fout("kruskal.out");
struct muchie
{
  int x,y,c;
};
struct muc
{
    int x,y;
};
muchie a[N];
muc v[N];
int t[N];
int n,m,k;
void Read()
{
    fin>>n>>m;
    for(int i=1;i<=m;i++)
    {
        fin>>a[i].x>>a[i].y>>a[i].c;
    }
}
int CMP(muchie A, muchie B)
{
    return A.c<B.c;
}
void Union(int x, int y)
{
    t[y]=x;
}
int Find(int x)
{
    int y,rad;
    rad=x;
    while(t[rad]!=0)
        rad=t[rad];
    while(x!=rad)
    {
        y=t[x];
        t[x]=rad;
        x=y;
    }
    return rad;
}
void Kruskal()
{
    int p,q,i,costmin=0;
    sort(a+1,a+m+1,CMP);
    for(i=1;i<=m;i++)
    {
        p=Find(a[i].x);
        q=Find(a[i].y);
        if(p!=q)
        {
            v[++k].x=a[i].x;
            v[k].y=a[i].y;
            costmin+=a[i].c;
            Union(p,q);
        }
    }
    fout<<costmin<<"\n";
    for(int i=1;i<=k;i++)
        fout<<v[i].x<<" "<<v[i].y<<"\n";
}
int main()
{
    Read();
    Kruskal();
    return 0;
}