#include <bits/stdc++.h>
using namespace std;
const int maxn = 2e6 + 5;
const int mod = 1e9 + 7;
map<int,int> mp;
int a[maxn];
void solve(){
      
  
   int n;
   cin >> n;
   mp.clear();
   for(int i = 1;i <= n ;i ++) cin >> a[i],mp[a[i]]++;
   int id = 0,id1 = 0;
   int mx = 0;
   for(auto [x,y] : mp){
   	    if(y >= mx) id1 = id,id = x,mx = y;
   }
   id1 = mp[id1];
   id = mp[id];
    mx = 0;
   for(int i = 0 ;i <= id1;i ++) mx = max(mx,id | i);
   cout << mx << endl;

}
int main(){
    

    int t = 1;
    cin >> t;
    while(t--){
    	solve();
    }	 
   return 0;
}