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[] data = new int[N];
		for(int i = 0 ; i<N; i++){
			data[i] = sc.nextInt();
		}
		Arrays.sort(data);
		long max = 0;
		long max2 = 0;
		for(int i = N-1; i>0; i--){
			if(data[i] == data[i-1]){
				if(max == 0){
					max = data[i];
					i--;
				}
				else{
					max2 = data[i];
					break;
				}
			}
		}
		long res = max*max2;
		System.out.println(res);
	}
}
