#include <cstdio>
#include <vector>
#include <algorithm>
#define INF 999999999
using namespace std;
vector < pair <int, int> > G[200005];
vector < pair <int, int> > apm;
int d[200005],t[200005],n,m,s,i,x,y,cost,crt,crt1,j,Min,numar;
bool used[200005];
int main()
{
    freopen("apm.in","r",stdin);
    freopen("apm.out","w",stdout);
    scanf("%d %d %d",&n,&m);
    s=1;
    for (i=1; i<=m; i++)
    {
        scanf("%d %d %d",&x,&y,&cost);
        G[x].push_back(make_pair(y,cost));
        G[y].push_back(make_pair(x,cost));
    }
    for (i=1; i<=n; i++) d[i]=INF;
    d[s]=0;
    used[s]=true;
    t[s]=0;
    crt=s;
    numar=1;
    while (numar<n)
    {
        for (j=0; j<G[crt].size(); j++)
        {
            if (G[crt][j].second<d[G[crt][j].first])
            {
                d[G[crt][j].first]=G[crt][j].second;
                t[G[crt][j].first]=crt;
            }
        }
        Min=INF;
        crt1=0;
        for (j=1; j<=n; j++) if (used[j]==false && d[j]<Min) Min=d[j],crt1=j;
        if (Min!=INF)
        {
            used[crt1]=true;
            apm.push_back(make_pair(t[crt1],crt1));
            crt=crt1;
            numar++;
        }
        else crt=t[crt];
    }
    for (i=0; i<apm.size(); i++) printf("%d %d\n",apm[i].first,apm[i].second);
    return 0;
}