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.Arrays;
import java.util.Scanner;
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);
		
		
		int h = 0;
		int w = 0;
		int count = 0;
		
		for(int i = n-1; i >= 1 ; i--) {
			if(a[i] == a[i-1]){
				count++;
				if(h == 0) {
					h = a[i];
				}
				if(count == 3) {
					w = a[i];
				}
				if(h != 0 && a[i] < h) {
					w = a[i];
				}
			}
		     else {
					count = 0;
				}
				
			if(h != 0 && w != 0) {
				break;
			}
		}
		
		System.out.println((long)h*w);
	}

}
