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.Collections;
import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);
		int N = scan.nextInt();
		long h = 0;
		long w = 0;
		Long[] A = new Long[N];
		for(int i = 0; i < N; i++) {
			A[i] = scan.nextLong();
		}
		Arrays.sort(A, Collections.reverseOrder());
		for(int i = 1; i < N; i++) {
			if(h == 0) {
				if(A[i - 1].equals(A[i])) {
					h = A[i];
					i++;
				}
			} else {
				if(A[i - 1].equals(A[i])) {
					w = A[i];
					break;
				}
			}
		}
		System.out.println((long)h * w);
		scan.close();

	}

}
