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){
		
		long h=0,w=0;
		
		@SuppressWarnings("resource")
		Scanner sc = new Scanner(System.in);
		
		int n = sc.nextInt();
		
		long[] array = new long[n];
		
		for(int i=0; i < n; i++){
			array[i] = sc.nextLong();
		}
		
		Arrays.sort(array);
		
		//System.out.println(array[0]);
		
		for(int i=array.length-1; i>0; i--){
			if(array[i] == array[i-1]){
				if(h == 0){
					h = array[i];
					i--;
				}
				else{
					w = array[i];
					System.out.println(h*w);
					return;
				}
			}
		}
		
		System.out.println("0");
		
	}

}