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.*;
import java.math.*;
public class Main{
  public static void main(String[] args){
    Scanner sc = new Scanner(System.in);
    int n = sc.nextInt();
    long[] a = new long[n];
    for(int i = 0; i < n; i++){
      a[i] = sc.nextLong();
    }
    Arrays.sort(a);
    long hen1 = 0;
    long hen2 = 0;
    for(int i = a.length-1; i >= 1; i--){
      if(a[i] == a[i-1]){
        if(hen1 == 0){
          hen1 = a[i];
          i--;
        }else{
          hen2 = a[i];
          break;
        }
      }
    }
    System.out.println(hen1 * hen2);
  }
}
