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
import java.util.Scanner;
import java.util.Arrays;

public class Main{
  public static void main(String[] args){
    Scanner scanner = new Scanner(System.in);
    int N = scanner.nextInt();
    int[] A = new int[N];
    long ans = 1;
    int count = 0;
    for (int i = 0; i < N; i++){
      A[i] = scanner.nextInt();
    }
    Arrays.sort(A);
    for (int i = N - 1; i > 0; i--){
      if (A[i] == A[i - 1]){
        ans *= A[i];
        i--;
        count++;
      }
      if (count >= 2){
      System.out.println(ans);
      return;
      }
    }
    System.out.println(0);
  }
}
