#include<iostream>
#include<cstdio>
#include<cstring>
#include<algorithm>
using namespace std;
const int maxn=3030;
const int inf=1e9;
int g[maxn];
int main()
{
    int n,m;
    while(~scanf("%d%d",&n,&m))
    {
        for(int i=0;i<maxn;i++)
            g[i]=0;
        int u,v,w;
        for(int i=0;i<m;i++)
        {
            scanf("%d%d%d",&u,&v,&w);
            if(u==v) continue;
            g[u]+=w;
            g[v]+=w;
        }
        int ans=inf;
        for(int i=1;i<=n;i++)
        {

            ans=min(ans,g[i]);
        }
        printf("%d\n",ans);
    }
    return 0;
}