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();
		int[] arr = new int[n];
		for (int i = 0; i < n; i++) {
		    arr[i] = sc.nextInt();
		}
		Arrays.sort(arr);
		HashSet<Long> set = new HashSet<>();
		long another = 0;
		for (int i = n - 1; i >= 0; i--) {
		    long a = arr[i];
		    if (set.contains(a)) {
		        if (another == 0) {
		            another = a;
		            set.remove(a);
		        } else {
		            System.out.println(another * a);
		            return;
		        }
		    } else {
		        set.add(a);
		    }
		}
        System.out.println(0);
	}
}
