#include<cstdio>
#include<cstring>
#include<algorithm>
typedef long long ll;
using namespace std;
int cas,n,m,s,f1,f2;
int f[1000000],a[1000000],b[1000000],c[1000000];
int find(int x){
    if (f[x]!=x)f[x]=find(f[x]);
    return(f[x]);
}
bool check(int x){
    int s=0;
    for (int i=1;i<=n;i++)f[i]=i;
    for (int i=1;i<=m;i++)
    if ((c[i]&x)==x){
        f1=find(a[i]);
        f2=find(b[i]);
        if (f1!=f2){
            f[f2]=a[i];
            s++;
        }
    }
    if (s==n-1)return 1;
    return 0;
}
int main(){
    scanf("%d",&cas);
    while(cas--){
        scanf("%d%d",&n,&m);
        for (int i=1;i<=m;i++)scanf("%d%d%d",&a[i],&b[i],&c[i]);
        int x=0;
        for (int p=30;p>=0;p--){
            int k=1<<p;
            int y=x+k;
            if (check(y))x=y;
        }
        printf("%d\n",x);
    }
}