#include <iostream>
#include <cstdio>
#include <algorithm>
#include <cstring>
using namespace std;

const int N=4000;
int n,m;
int sum[N];
int u,v,w;

int main()
{
#ifdef LOCAL
    freopen("in.txt","r",stdin);
#endif
    while(~scanf("%d%d",&n,&m))
    {
        memset(sum,0,sizeof(sum));
        for(int i=0; i<m; i++)
        {
            scanf("%d%d%d",&u,&v,&w);
            if(u==v)continue; 
            sum[u]+=w;
            sum[v]+=w;
        }
        sort(sum+1,sum+1+n);
        printf("%d\n",sum[1]);
    }

}