//HDU 5627

#include <bits/stdc++.h>

using namespace std;

const int maxn = 3e5+6;

int x[maxn], y[maxn], w[maxn], flag[maxn], fa[maxn];

int find_set(int x){if(x == fa[x]) return x; return fa[x] = find_set(fa[x]);}

void union_set(int x, int y){x = find_set(x), y = find_set(y); if(x!=y) fa[x] = y;}

int n, m;

int main(){

    int T; scanf("%d", &T);

    while(T--){

        scanf("%d%d", &n, &m);

        for(int i = 1; i <= m; i++) scanf("%d%d%d", &x[i], &y[i], &w[i]);

        int ans = 0;

        for(int i = 30; i >= 0; i--){

            for(int j = 1; j <= n; j++) fa[j] = j;

            for(int j = 1; j <= m; j++){

                if((w[j]&ans) == ans && (w[j]>>i&1)) flag[j] = 1;

                else flag[j] = 0;

            }

            for(int j = 1; j <= m; j++){

                if(flag[j]){

                    union_set(x[j], y[j]);

                }

            }

            bool ok = 1;

            int p = find_set(1);

            for(int j = 2; j <= n; j++){

                if(find_set(j) != p){

                    ok = 0;

                }

            }

            if(ok) ans |= (1<<i);

        }

        printf("%d\n", ans);

    }

    return 0;

}