#include <cstdlib>
#include <iostream>
#include <vector>
#include <cstdio>
#include <cstring>
#include <algorithm>

using namespace std;

int main(){
    int ans[3005],n,m;
    while(~scanf("%d%d",&n,&m)){
        memset(ans,0,sizeof(ans));
        for(int i = 0;i < m;i++){
            int u,v,w;
            scanf("%d%d%d",&u,&v,&w);
            if(u != v) ans[u] += w,ans[v] += w;
        }
        int minn = 0x3f3f3f3f;
        for(int i = 1;i <= n;i++)
            minn = min(minn,ans[i]);
        printf("%d\n",minn);
    }
    return 0;
}