We have N sticks with negligible thickness. The length of the i-th stick is A_i.

Snuke wants to select four different sticks from these sticks and form a rectangle (including a square), using the sticks as its sides. Find the maximum possible area of the rectangle.

Constraints

* 4 \leq N \leq 10^5
* 1 \leq A_i \leq 10^9
* A_i is an integer.

Input

Input is given from Standard Input in the following format:


N
A_1 A_2 ... A_N


Output

Print the maximum possible area of the rectangle. If no rectangle can be formed, print 0.

Examples

Input

6
3 1 2 4 2 1


Output

2


Input

4
1 2 3 4


Output

0


Input

10
3 3 3 3 4 4 4 5 5 5


Output

20
#include <bits/stdc++.h>
using namespace std;

int main() {
  long N;
  cin >> N;
  vector<long> A(N);
  for (long i = 0; i < N; i++) cin >> A.at(i);
  sort(A.rbegin(), A.rend());
  
  long a = 0, b = 0;
  for (long i = 0; i + 1 < N; i++) {
    if (A.at(i) == A.at(i + 1)) {
      if (!a) a = A.at(i++);
     
      else b = A.at(i++);
        
      if (b) break;
    }
  }
  cout << a * b << "\n";
}
