#include<cstdio>
#include<cstring>
#define M 100010
#define N 3005
using namespace std;
int n,m;
struct u2003{
    int b,nx,va;
}e[2*M];
int head[N],last=1;
inline void build(int a,int b,int c){
    e[++last].b=b;
    e[last].nx=head[a];
    head[a]=last;
    e[last].va=c;
}
inline bool scan(){
    if(scanf("%d%d",&n,&m)==EOF)return 0;
    
    last=1;
    memset(head,0,4*(n+2));
    
    for(int i=1;i<=m;i++){
        int a,b,c;
        scanf("%d%d%d",&a,&b,&c);
        if(a==b)continue;
        build(a,b,c);
        build(b,a,c);
    }
    return 1;
}
int dfn[N],low[N];
int times;
void tarjan(int x){
    dfn[x]=low[x]=++times;
    for(int i=head[x];i;i=e[i].nx){
        int y=e[i].b;
        if(!dfn[y])tarjan(y);
    }
}
inline int suan(){
    times=0;
    memset(dfn,0,4*(n+2));
    tarjan(1);
    for(int i=1;i<=n;i++)
        if(!dfn[i])return 0;
    int ans=0x3f3f3f3f;
    for(int x=1;x<=n;x++){
        int zhi=0;
        for(int i=head[x];i;i=e[i].nx)
            zhi+=e[i].va;
        if(zhi)ans=ans<zhi?ans:zhi;
    }
    return ans;
}
int main(){
    while(scan())
        printf("%d\n",suan());
    return 0;
}