#include<iostream>
#include<algorithm>
#include<string.h>
using namespace std;
int main() {
    int sum[3010];
    int n, m;
    while (cin >> n >> m) {
        memset(sum, 0, sizeof(sum));
        int u, v, w;
        for (int i = 0; i < m; i++) {
            cin >> u >> v >> w;
            if (u == v)continue;
            sum[u] += w;
            sum[v] += w;
        }
        sort(sum + 1, sum + n + 1);
        cout << sum[1] << endl;
    }

}