#include<cstdio>
#include<cstring>
#include<algorithm>
#include<cmath>
#include<iostream>
using namespace std;
const int N=3007;
int sum[N],aa[N];
int digui(int x)
{
    if(aa[x]==0)
        return x;
    return aa[x]=digui(aa[x]);
}
void init()
{
    for(int i=0;i<N;i++)
    {
        aa[i]=0;sum[i]=0;
    }
}
int main()
{
    int n,m,i,x,y,z,cnt,t1,t2;
    while(cin>>n>>m)
    {
        cnt=n-1;
        init();
        for(i=1;i<=m;i++)
        {
            cin>>x>>y>>z;
            if(x==y)
                continue;
            sum[x]+=z;
            sum[y]+=z;
            t1=digui(x);
            t2=digui(y);
            if(t1!=t2)
            {
                aa[t1]=t2;
                cnt--;
            }
        }
        if(!cnt)
        {
            sort(sum+1,sum+n+1);
            cout<<sum[1]<<endl;
        }
        else
            cout<<0<<endl;
    }
    return 0;
}