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.ArrayList;
import java.util.Collections;
import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		ArrayList<Long> nums = new ArrayList<Long>();
		Scanner sc 	   = new Scanner(System.in);
		long N = sc.nextInt();
		long height=0,width=0;
		for(int i=0;i<N;i++) 
		{
			long a = sc.nextInt();
			nums.add(a);
		}
		Collections.sort(nums);
		Collections.reverse(nums);
		
		for(int i=1;i<nums.size();i++) 
		{
			long a = nums.get(i-1);
			long b = nums.get( i );
			if(a==b) 
			{
				 if		(height == 0)  height	 =	a;
				 else if(height != 0) { width	 =	a; break; }
				 nums.remove(i);nums.remove(i-1);i--;

			}
		}
		 System.out.println(height * width);
		
	}

}
