#include <iostream>
#include <queue>
#include <algorithm>

using namespace std; 

int main(){
    int n, m;

    while(cin >> n >> m)
    {

        int *weight = new int[n];
        bool **connect = new bool *[n];
        for(int i = 0; i < n; i++){
            connect[i] = new bool[n];
        }

        for(int i = 0; i < n; i++){
            weight[i] = 0;
            for(int j = 0;  j < n; j++){
                connect[i][j] = false;
            }
        }

        int u, v, w;
        for(int i = 0; i < m; i++){
            cin >> u >> v >> w;

            if(u == v){
                continue;
            }

            u--;
            v--;
            weight[u] += w;
            weight[v] += w;
            connect[u][v] = true;
            connect[v][u] = true;
        } 

        // 判断连通图
        queue<int> q;
        q.push(0);
        bool *visited = new bool[n];

        while(!q.empty()){
            int node = q.front();
            q.pop();
            visited[node] = true;
            
            for(int i = 0; i < n; i++){
                if(connect[node][i] > 0 and !visited[i]){
                    q.push(i);
                }
            }
        }

        bool end = false;
        for(int i = 0; i < n; i++){
            if(!visited[i]){
                cout << 0 << endl;
                end = true;
                break;
            }
        }
        if(end){
            continue;
        }

        // 最小值
        cout << *min_element(weight, weight + n) << endl;
    }
}