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.*;
public class Main{

  public static void main(String[] args){
      Scanner sc = new Scanner(System.in);
      int n = sc.nextInt();

      int[] arr = new int[n];
      for(int i = 0; i < n; i++)
        arr[i] =  sc.nextInt();
      Arrays.sort(arr);
      long h = 0;
      long w = 0;
      int i = arr.length - 1;
      for(; i > 0; i--) {
        if(arr[i] == arr[i-1]) {
            h = arr[i];
            i-=2;
            break;
        }
      } 
      for(; i > 0; i--) {
        if(arr[i] == arr[i-1]) {
            w = arr[i];
            break;
        }
      }
      System.out.println(h*w);
  }
}
