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 sc = new Scanner(System.in);
    int n = sc.nextInt();
    long max1 = 0;
    long max2 = 0;
    long[] a = new long[n];
    for(int i = 0; i<n; i++){
      a[i] = sc.nextLong();
    }
    Arrays.sort(a);
    for(int i = n-1; i>0; i--){
      if(a[i-1] == a[i]){
        max1 = a[i];
        for(int j = i-2; j > 0; j--){
          if(a[j-1] == a[j]){
            max2 = a[j];
            System.out.println(max1*max2);
            return;
          }
          if(j ==1){
            System.out.println(0);
            return;
          }
        }
      }
    }
    System.out.println(0);
  }
}
