/************************************************
 *Author*        :ZZZZone
 *Created Time*  : 日  8/ 6 10:18:56 2017
*********************************************/

#include <cstdio>
#include <cstring>
#include <iostream>
#include <algorithm>
#include <vector>
#include <queue>
#include <set>
#include <map>
#include <string>
#include <cmath>
#include <cstdlib>
#include <ctime>
#include <stack>
using namespace std;
typedef pair<int, int> PII;
typedef long long LL;
typedef unsigned long long ULL;
const int MaxN = 1e5;
int sum[MaxN + 5];
int n, m;

int main()
{
    //freopen("in.txt", "r", stdin);
    //freopen("out.txt", "w", stdout);
    while(~scanf("%d %d", &n, &m)){
        memset(sum, 0, sizeof(sum));
        for(int i = 1;  i <= m; i++){
            int u, v, w;
            scanf("%d %d %d", &u, &v, &w);
            if(u != v){
                sum[u] += w;
                sum[v] += w;
            }
        }
        int ans = 1 << 30;
        for(int i = 1; i <= n; i++) ans = min(ans, sum[i]);
        printf("%d\n", ans);
    }
    return 0;
}