#include <iostream>  
#include <algorithm>    
#include <cstdio>   
#include <cmath>
#include <cstring>
using namespace std;    
int father[3010];  
int M,N;  
int a,b,w;  
int find(int x){  
    while(x!=father[x])  
    x=father[x];  
    return x;  
}   
int main()    
{    
    int i,j;  
    int x,y;  
    int sum[3010];
    while(cin>>N>>M){      
        j=1;  
        memset(sum,0,sizeof(sum));
        for(i=1;i<=N;i++)    
        father[i]=i; 
        for(i=1;i<M+1;i++)    
        {  
            scanf("%d %d %d",&a,&b,&w); 
            if(a==b)continue;//?????
            sum[a]+=w;
            sum[b]+=w;
            x=find(a);  
            y=find(b);     
            if(x!=y){    
                j++;   
                father[x]=y;    
            }    
        }    
        if(j==N) {
            sort(sum+1, sum+N+1);
            printf("%d\n",sum[1]); 
        }     
        else printf("0\n");     
    }    
    return 0;    
}