#include <bits/stdc++.h>
#define mem(a, b) memset(a, b, sizeof(a))
#define inf (1e9 + 7)
using namespace std;

int n, m, v[3005];

int main()
{
    while(~scanf("%d%d", &n, &m))
    {
        mem(v, 0);
        for(int i = 1, a, b, c;i <= m;i++)
        {
            scanf("%d%d%d", &a, &b, &c);
            if(a != b)
                v[a] += c, v[b] += c;
        }
        int ans = inf;
        for(int i = 1;i <= n;i++)
            ans = min(ans, v[i]);
        printf("%d\n", ans);
    }
    return 0;
}