#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<cmath>
#include<algorithm>

#define ll long long
#define inf 1e9
#define eps 1e-10
#define md
#define N 300010
using namespace std;
struct PP { int x,y,l;} p[N];
bool ok[N];
int fa[N];
int find(int x) { return fa[x]==x?x:fa[x]=find(fa[x]);}
int main()
{
    int tt;
    scanf("%d",&tt);
    while (tt--)
    {
        int n,m;
        scanf("%d%d",&n,&m);
        for (int i=1;i<=m;i++)
        {
            scanf("%d%d%d",&p[i].x,&p[i].y,&p[i].l);
        }
        int ans=0;
        memset(ok,1,sizeof(ok));
        for (int k=30;k>=0;k--)
        {
            for (int i=1;i<=n;i++) fa[i]=i;
            int tot=n;
            for (int i=1;i<=m;i++)
            {
                if ( (!(p[i].l&(1<<k))) || (!ok[i]) ) continue;
                int f1=find(p[i].x),f2=find(p[i].y);
                if (f1!=f2)
                {
                    fa[f1]=f2;
                    tot--;
                }
            }
            if (tot==1)
            {
                ans+=1<<k;
                for (int i=1;i<=m;i++)
                    if (!(p[i].l&(1<<k))) ok[i]=0;
            }
        }
        printf("%d\n",ans);
    }
    return 0;
}