#include<cstdio>
#include<cstring>
#include<iostream>
#include<algorithm>
#define int long long
#define rep(i,a,b) for(int i=a;i<=b;i++)
#define per(i,a,b) for(int i=a;i>=b;i--)
using namespace std;

const int N=3e6+10;

int n,m,a[N];

signed main(){
    cin.tie(0)->sync_with_stdio(false);
    while(cin>>n>>m){
        int u,v,w;
        memset(a,0,sizeof a);
        rep(i,1,m){
            cin>>u>>v>>w;
            if(u==v) continue;
                a[u]+=w;
                a[v]+=w;
        }
        sort(a+1,a+n+1);
        cout<<a[1]<<endl;
    }
    return 0;
}