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) throws Exception{
		Scanner stdIn=new Scanner(System.in);
		int N=stdIn.nextInt();
		int A[]=new int[N];
		int z=0;
		long x=0,y=0;
		while(z<N){
			A[z]=stdIn.nextInt();
			z++;
		}z=N-1;
		Arrays.sort(A);
		while(z>0){
			if(A[z]==A[z-1]){
				if(y==0)
					y=A[z];
				else
					if(x==0)
						x=A[z];
					else
						break;
				z--;
			}
			z--;
		}
		if(x==0||y==0)
			System.out.println(0);
		else
			System.out.println(y*x);
	}
}
