#include<bits/stdc++.h>
using namespace std;
ifstream F("apm.in");
ofstream G("apm.out");
#define N 200001
vector<pair<int,int> > g[N];
bitset<N> r;
int m,n,i,j,k,p[N],d[N],h[2*N],l,t,w,f,y,z[N];
int main()
{
    for(F>>n>>m;m--;F>>i>>j>>k,g[i].push_back({j,k}),g[j].push_back({i,k}));
    for(i=1;i<=n;d[i]=p[i]=N,++i);
    for(d[1]=0,k=p[1]=h[1]=1;k;) {
        for(t=h[1],h[1]=h[k--],p[h[1]]=w=1;(w<<1)<=k;swap(h[w],h[f]),p[h[w]]=w,p[h[f]]=f,w=f)
            if(f=w<<1,f<k&&d[h[f+1]]<d[h[f]]?++f:0,d[h[w]]<=d[h[f]])
                break;
        if(!r[t])
            for(y+=d[t],r[t]=1,i=0,l=g[t].size();i<l;++i)
                if(f=g[t][i].first,w=g[t][i].second,!r[f]&&d[f]>w)
                    for(d[f]=w,z[f]=t,p[f]==N?h[++k]=f,p[h[k]]=k:0,w=p[f];w>1&&d[h[w>>1]]>d[h[w]];f=w>>1,swap(h[w],h[f]),p[h[w]]=w,p[h[f]]=f,w=f);
    }
    for(G<<y<<'\n'<<n-1<<'\n',i=2;i<=n;G<<z[i]<<' '<<i<<'\n',++i);
    return 0;
}