#include <bits/stdc++.h>
using namespace std;

int n, m, u, v, w, c[3010];
int main() {
    while(~scanf("%d%d", &n, &m)) {
        int ans = INT_MAX;
        memset(c, 0, sizeof(c));
        for(int i = 0; i < m; i++) {
            cin >> u >> v >> w;
            if(u == v) continue;
            c[u] += w;
            c[v] += w;
        }
        for(int i = 1; i <= n; i++) ans = min(ans, c[i]);
        cout << ans << endl;
    }
}