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

const int maxn = 3030;
const int maxm = 100100;
const int inf = 2147483647;
int n, m;
int G[maxn][maxn];
int in[maxn];

signed main() {
    // freopen("in", "r", stdin);
    int u, v, w;
    while(~scanf("%d%d",&n,&m)) {
        memset(G, 0, sizeof(G));
        memset(in, 0, sizeof(in));
        for(int i = 0; i < m; i++) {
            scanf("%d%d%d",&u,&v,&w);
            if(u != v) {
                in[u] += w;
                in[v] += w;
            }
        }
        int ret = inf;
        for(int i = 1; i <= n; i++) {
            ret = min(ret, in[i]);
        }
        printf("%d\n", ret);
    }
    return 0;
}