#include <bits/stdc++.h>
using namespace std;
int main()
{
    int mp[10000];
    int n, m, u, v, w, minl;
    while (cin >> n >> m)
    {
        minl = 100000;
        memset(mp, 0, sizeof(mp));
        for (int i = 0; i < m; ++i)
        {
            cin >> u >> v >> w;
            if (v != u)
            {
                mp[v] += w;
                mp[u] += w;
            }
        }
        for (int i = 1; i <= n; ++i)
            minl = min(minl, mp[i]);
        cout << minl << endl;
    }
    return 0;
}