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 array[] = new long[n];
	        long arr[] = new long[2];
	        for (int i = 0; i < n; i++) {
	            array[i] = sc.nextInt();
	        }
	        Arrays.sort(array);
	        int count = 0;
	        for (int i = n - 1; i >= 1; i--) {
	            if (array[i] == array[i - 1]) {
	                arr[count] = array[i];
	                count++;
	                i--;
	            }
	            if (count == 2) {
	                break;
	            }
	        }
	        System.out.println(arr[0] * arr[1]);

	    }
}
