#include<cstdio>
#include<cstring>
#include<algorithm>
using namespace std;
int ans[3001];
int main()
{
    int n,m;
    while(scanf("%d%d",&n,&m) != EOF)
    {
        int  u,v,w;
        memset(ans,0,sizeof(ans));
        for(int i = 1;i <= m;i++)
        {
            scanf("%d %d %d",&u,&v,&w);
            if(u==v) continue;
            ans[u] += w;
            ans[v] += w;
        }
        sort(ans+1,ans+n+1);
        printf("%d\n",ans[1]);
    }
    return 0;
}