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[] x=new int[n];
		for(int i=0;i<n;i++){
			x[i]=sc.nextInt();
		}
		Arrays.sort(x);
		long sum=1,t=0;
		for(int i=n-1;i>=1;i--){
			if(x[i]==x[i-1]){
				t++;
				sum*=x[i];
				i--;
			}
			if(t==2)
				break;
				
		}
		if(t<2)
			sum=0;
		System.out.print(sum);
	}
}