#include<cstdio>
#include<cstring>
#include<algorithm>
#include<stack>
#include<vector>
using namespace std;
const int maxn = 3005;
const int maxm = 100005;
int cost[maxn];
int n,m;
int main()
{
    int u,v,w;
    while(scanf("%d%d",&n,&m)!=EOF)
    {
        memset(cost,0,sizeof(cost));
        for(int i=0;i<m;i++)
        {
            scanf("%d%d%d",&u,&v,&w);
            if(u==v) continue;
            cost[u] += w;
            cost[v] += w;
        }
        int res = cost[1];
        for(int i=2;i<=n;i++) res = min(res,cost[i]);
        printf("%d\n",res);
    }
    return 0;
}