#include <iostream>
#include <algorithm>
#include <cstdio>
#include <string.h>
using namespace std;
int main()
{
    int m,n;
    int sum[10000];
    while(~scanf("%d%d",&n,&m))
    {
        memset(sum,0,sizeof(sum));
        for(int i=1; i<=m; i++)
        {
            int a,b,c;
            cin>>a>>b>>c;
            if(a==b)
                continue;
            sum[a]+=c,sum[b]+=c;
        }
        sort(sum+1, sum+n+1);
        cout<<sum[1]<<endl;
    }
    return 0;
}