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[] srgs) {
    Scanner sc = new Scanner(System.in);
    int n = Integer.parseInt(sc.next());
    int[] edge = new int[n];
    for(int i = 0; i < n; i++) edge[i] = Integer.parseInt(sc.next());
    Arrays.sort(edge);
    long area = 0;
    long temp = 0;
    boolean flag = false;
    for(int i = n - 1; i > 0; i--) {
      if(!flag && edge[i] == edge[i - 1]) {
        temp = edge[i];
        edge[i - 1] = -1;
        flag =true;
      } else if(flag && edge[i] == edge[i - 1]) {
        area = temp * edge[i];
        break;
      }
    }
    System.out.println(area);
  }
}
