#include <cstdio>
#include <cstring>
#include <algorithm>

using namespace std;

const int N = 3100;

int sum[N];
int n, m;

int main() {
    while(~scanf("%d%d", &n, &m)) {
        memset(sum, 0, sizeof sum);
        for(int i = 1; i <= m; i ++) {
            int u, v, w;
            scanf("%d%d%d", &u, &v, &w);
            if(u == v) continue;
            sum[u] += w, sum[v] += w;
        }
        sort(sum + 1, sum + n + 1);
        printf("%d\n", sum[1]);
    }
    return 0;
}