/*
* @FileName: D:\代码与算法\2017训练比赛\百度之星\1002-pro.cpp
* @Author: Pic
* @Date:   2017-08-06 09:31:11
* @Last Modified time: 2017-08-06 09:34:31
*/

#include <iostream>
#include <algorithm>
#include <cstdio>
#include <string.h>
#include <queue>
using namespace std;
int sum[3000+30];
int main(){
    int n,m;
    while(~scanf("%d%d",&n,&m)){
        memset(sum,0,sizeof(sum));
        int u,v,w;
        for(int i=0;i<m;i++){
            scanf("%d%d%d",&u,&v,&w);
            if(u!=v){
                sum[u]+=w;
                sum[v]+=w;
            }
        }
        int ans=0x3f3f3f3f;
        for(int i=1;i<=n;i++){
            ans=min(ans,sum[i]);
        }
        printf("%d\n",ans);
    }
    return 0;
}