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 <iostream>
#include <algorithm>

using namespace std;

int A[110000];

int main() {
  int N;
  cin >> N;
  for(int i = 0; i < N; i++) cin >> A[i];
  sort(A, A + N, greater<int>());
  
  int i = 0, j = 0;
  long long e[2] = { };
  while(i < N && j < 2) {
    if(A[i] == A[i + 1]) {
      e[j] = A[i];
      i += 2;
      j++;
    } else {
      i++;
    }
  }
  cout << e[0] * e[1] << endl;
  
  return 0;
}