#include <iostream>
#include <cstring>
#include <algorithm>
using namespace std;
const int N = 3010,M=100010;
int n,m;

int p[N];
int find(int x)  // 并查集
{
    if (p[x] != x) p[x] = find(p[x]);
    return p[x];
}
int sum[N];
int main()
{
    while(scanf("%d%d",&n,&m)!=EOF)
    {
        int cnt=0;
        memset(sum,0,sizeof sum);
        for(int i=1;i<=n;i++)p[i]=i;
        while (m -- )
        {
            int a,b,c;
            scanf("%d%d%d",&a,&b,&c);
            if(a==b)continue;
           sum[a]+=c;
           sum[b]+=c;
           a=find(a),b=find(b);
           if(a!=b)
           {
               p[a]=b;
               cnt++;
           }
        }
        if(cnt==n-1)
        {
            sort(sum+1,sum+1+n);
            cout<<sum[1]<<endl;
        }
        else puts("0");
    
    }
    return 0;
}