#include<iostream>
#include<cstring>
#include<queue>
using namespace std;
int n,e,g[105][105],r,s,t;
bool flag[105];
struct Edge{
    int from,id,w;
    Edge(){};//用来实现创建节点
    Edge(int argfrom,int argid,int argw){
        from=argfrom;
        id=argid;
        w=argw;
    }
    friend bool operator<(Edge a,Edge b){
        return a.w>b.w; //完成队列升序操作
    }
};
priority_queue<Edge> pque;  //operator操作函数辅助小根堆实现
vector<Edge> Prim(int sid){
    vector<Edge> result;//矢量列表
    memset(flag,false,sizeof(flag));
    pque.push(Edge(-1,sid,0));
    while(result.size()<n-1){
        Edge ed=pque.top();
        pque.pop();
        if(flag[ed.id])continue;
        flag[ed.id]=true;
        if(ed.from!=-1)result.push_back(ed);//追加到结果列表
        for(int i=1;i<=n;++i){ //以白点开始扫描 邻接各边
            if(!flag[i] && g[ed.id][i]<0x3f3f3f3f){
                pque.push(Edge(ed.id,i,g[ed.id][i]));
            }
        }  
    }
    return result;
}
int main(){
    memset(g,0x3f,sizeof(g));
    cin>>n>>e;
    for(int i=1;i<=e;++i){
        cin>>r>>s>>t;
        g[r][s]=g[s][r]=t;
    }
    vector<Edge>Edges=Prim(1);
    for(int i=0;i<Edges.size();++i){
        cout<<Edges[i].from<<" "<<Edges[i].id<<endl;
    } 
    return 0;
}//网 pass