#include <bits/stdc++.h>
#define boAshraf ios_base::sync_with_stdio(false); cin.tie(NULL);
#define ll long long
#define sz(s) (int)(s).size()
#define all(s) (s).begin(),(s).end()
using namespace std;
void File();
void sol();
int main() {
    boAshraf
    File();
    int t = 1;
    cin >> t;
    while (t--) {
        sol();
    }
    return 0;
}

void sol() {
    int n,k;
    cin>>n>>k;
    vector<int>v(n);
    for(auto &it:v)cin>>it;
    int ans=0;
    for(int i=0;i<=19;i++){
        if((ans>>i)&1)continue;
        for(auto it:v){
            if((it>>i)&1){
                ans|=it;break;
            }
        }
    }
    cout<<ans<<'\n';
}

void File() {
// #ifndef ONLINE_JUDGE
    freopen("looking.in", "r", stdin);
    // freopen("output.txt", "w", stdout);
// #endif
}