#include<bits/stdc++.h>
using namespace std;
const int maxn=3e3+5;
int daijia[maxn]={0};
int main()
{
    int n,m;
    while(cin>>n>>m){
        memset(daijia,0,sizeof(daijia));
        int u,v,w;
        for(int i=0;i<m;i++){
           cin>>u>>v>>w;
           if(u==v)continue;
           daijia[u]+=w;
           daijia[v]+=w;
        }
        sort(daijia+1,daijia+n+1);
        cout<<daijia[1]<<endl;
    }

}