#include <iostream>
#include <cstring>
#include <algorithm>
using namespace std;

const int N = 3005;

int p[N];
int res[N];

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

int main()
{
    int n,m;
    while(cin >> n >> m)
    {
        int ans = 1; 
        for(int i = 1; i <= n; i++ ) p[i] = i;
        memset(res,0,sizeof res);
        while(m--)
        {
            int a,b,c;
            cin >> a >> b >> c;
            if(a == b) continue;
            int u = find(a);int v = find(b);
            res[a] += c;
            res[b] += c;
            if(u != v)
            {
                ans++;
                p[u] = v;
            }
        }
        if(ans == n)
        {
            sort(res + 1,res + 1 + n);
            cout << res[1] << endl;
        }
        else cout << 0 << endl;
    }
}