#include<fstream.h>
#include<stdlib.h>
#define NM  200001
#define MM  400001
#define endl "\n"
ifstream in("apm.in");
ofstream out("apm.out");
struct muchie{ int x,y,c; };

int n,m,L[NM];

muchie v[NM],h[NM];
void citire()
 { int i;
   in>>n>>m;
   for(i=0;i<m;i++)
		in>>v[i].x>>v[i].y>>v[i].c;
  }
int fcmp(void const*a,void const*b)
  { return ((muchie*)a)->c-((muchie *)b)->c;
   }
int main()
  { int i,ms=0,ct=0,j;
    citire();
    qsort(v,m,sizeof(v[0]),fcmp);
    for(i=1;i<=n;i++) L[i]=i;
    i=0;
    while(ms<n-1)
	    { while(L[v[i].x]==L[v[i].y]) i++;
	    h[ms]=v[i];
	    ms++;
	    ct+=v[i].c;
	    for(j=1;j<=n;j++)
		  if(L[j]==L[v[i].y])  L[j]=L[v[i].x];
	  }
   out<<ct<<endl;
   for(i=0;i<n-1;i++)
	  out<<h[i].x<<" "<<h[i].y<<" "<<endl;
 }