#include<cstdio>
#include<iostream>
#include<cstring>
using namespace std;
const int mn=3003,mm=200005;
int m,n;
int val[mn];
int main(){
    while(~scanf("%d%d",&n,&m))
    {
        memset(val,0,sizeof(val));
        for(int i=0;i<m;++i)
        {
            int u,v,w;
            scanf("%d%d%d",&u,&v,&w);
            if(u!=v)
            val[u]+=w,val[v]+=w;
        }
        int mi=INT_MAX;
        for(int i=1;i<=n;++i)
        mi=min(mi,val[i]);
        printf("%d\n",mi);
    }
    return 0;
}