#define _CRT_SECURE_NO_WARNINGS
#include<cstdio>
#include<cstring>
#include<algorithm>
#include<string>
#include<stack>
#include<vector>
#define MAX 20
typedef long long ll;
using namespace std;
const int maxn = 2e3 + 10;
typedef long long ll;
int mp[3010];
int main()
{
    int n, m;
    while (scanf("%d%d", &n, &m) != EOF)
    {
        memset(mp, 0, sizeof(mp));
        int u, v, w;
        while (m--)
        {
            scanf("%d%d%d", &u, &v, &w);
            if (u == v)
                continue;
            mp[u] += w;
            mp[v] += w;
        }
        sort(mp + 1, mp + n + 1);
        printf("%d\n", mp[1]);
    }
    return 0;
}