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();
    }
    Arrays.sort(A, Comparator.reverseOrder());
    ArrayList<Long> sides = new ArrayList<>();
    boolean flag = false;
    long result = 0;

    for(int i = 0; i < A.length - 1; i++) {
      long bar1 = A[i];
      long bar2 = A[i + 1];
      if (bar1 == bar2 && !flag) {
        sides.add(bar1);
        flag = true;
      } else {
        flag = false;
      }
      if (sides.size() == 2) {
        result = sides.get(0) * sides.get(1);
        break;
      }
    }
    System.out.println(result);
  }
}