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();
    long[] A = new long[N];

    for (int i = 0; i < N; i++) {
      A[i] = sc.nextLong();
    }

    sc.close();

    Arrays.sort(A);

    int count = 1;
    long tate = 0;
    long yoko = 0;

    for (int i = N-1; 0 < i; i--) {
      if (A[i] == A[i-1]) {
        count++;
      } else {
        count = 1;
      }
      if (count == 2) {
        if (tate == 0) {
          tate = A[i];
          count = 0;
        } else if (yoko == 0) {
          yoko = A[i];
          break;
        }
      }

    }

    System.out.println(tate * yoko);

  }

}