#include<bits/stdc++.h>
signed main()
{
    int res[5000]={0},n,m;
    while ( ~scanf("%d%d",&n,&m) )
    {
        for ( int i=1;i<=n;i++ ) res[i]=0;
        for ( int i=1;i<=m;i++ )
        {
            int u,v,w;scanf("%d%d%d",&u,&v,&w);
            if ( u!=v ) res[u]+=w,res[v]+=w;
        }
        int ans=1<<30;
        for ( int i=1;i<=n;i++ ) ans=std::min(ans,res[i]);
        printf("%d\n",ans);
    }
    return 0;
}