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[] a = new int[n];
		for(int i=0;i<n;i++) {
			a[i] = sc.nextInt();
		}
		
		Arrays.sort(a);
		
		long w = 0, h = 0, num = a[n-1];
		for(int i=n-2;i>=0;i--) {
			if(a[i]==num) {
				if(w==0) {
					w = num;
					if(i-1>=0) {
						num = a[i-1];
						i--;
					}
				}
				else if(h==0)
					h = num;
			}
			else {
				num = a[i];
			}
			
			if(w!=0 && h!=0)
				break;
		}
		
		System.out.println(w*h);
	}
}