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