1 #include <iostream>
 2 #include <cstdio>
 3 #include <algorithm>
 4 using namespace std;
 5 typedef long long ll;
 6 
 7 int a[100005], n;
 8 
 9 int main()
10 {
11     int t;
12     cin >> t;
13     while (t--)
14     {
15         ll maxn = 0;
16         cin >> n;
17         for (int i = 0; i < n; i++)
18         {
19             cin >> a[i];
20         }
21         sort(a, a + n);
22         for (int i = 1; i < n; i++)
23         {
24             maxn = max(maxn, (ll)a[i] * a[i - 1] * (a[i] & a[i - 1]));
25         }
26         cout << maxn << endl;
27     }
28     return 0;
29 }