#include<iostream>
#include<cstdio>
#include<algorithm>
#include<cstring>
#include<map>
using namespace std;
int n,m,c[3010],x,y,z;
int main() {
    while(scanf("%d%d",&n,&m)!=EOF) {
        memset(c,0,sizeof(c));
        for(int i=1;i<=m;i++) {
            scanf("%d%d%d",&x,&y,&z);
            if(x==y) continue;
            c[x]+=z;
            c[y]+=z;
        }
        sort(c+1,c+1+n);
        printf("%d\n",c[1]);
    }
    return 0;
} 
/*
3
1 2 3
8 0 4
7 6 5
1 2 3
5 6 7
4 0 8
*/