#include<iostream>
#include<string.h>
#include<algorithm>
#include<stdio.h>
using namespace std;

struct node
{
    int u;
    int v;
    int w;
}edge[120];

int cmp(node A, node B)
{
    if(A.w < B.w) return 1;
    else return 0;
}

//定义父节点 
int fa[120];

int find(int x)
{
    int p =fa[x];
    while(p != fa[p]) p =fa[p];
    return p;
}

int main()
{
    int n, m;//道路条数n 村庄个数m
    
    //输入 
    while(cin >> n >> m && n != 0 && m != 0)
    {
        //初始化，每个节点的父节点是其本身 
        for(int i = 1; i <= m; i++)
        {
            fa[i] = i;
        }
        
        for(int i = 0; i < n; i++)
        {
            cout<<edge[i].u<<edge[i].v<<edge[i].w<<endl;
        }
        sort(edge,edge + n,cmp);
        int sum = 0;//总路程
        int count = 0;//计数 
        for(int i = 0; i < n; i++)
        {
            int fx = find(edge[i].u);
            int fy = find(edge[i].v);
            if(fx != fy)
            {
                fa[fx] = fy;
                sum += edge[i].w;
                count++;
            }
        }
        if(count == M-1) cout<<sum<<endl;
        else cout<<"?"<<endl;
    }
    return 0;
}