#include <bits/stdc++.h>
#include <iostream>
#include <algorithm>
#include <stdio.h>
const int Max = 100 * 100 * 100 + 5;
#define LL long long
LL mod = 1e9+7;
const LL INF = 1e9;
//const int inx = INT_MAX;
using namespace std;
//  srand(time(NULL));
//      m = rand() % 1000 + 1;
//定义i i(A) i+n i+n(B) i+n+n i+n+n(C)
//bitset<Max>s,q;

LL a[3005];
int main()
{
    LL n,m,u,v,w;
    while(cin >> n >> m){
        memset(a,0,sizeof(a));
        int i,j;
        for(i = 1; i <= m; i++){
            cin >> u >> v >> w;
            if(u == v) continue;
            a[u] += w;
            a[v] += w;    
        }
        LL temp = INF;
        for(i = 1; i <= n; i++){
            if(a[i] <= temp) temp = a[i];
        }
        cout << temp << endl;
    }
    return 0;
}