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) {
		Scanner scan = new Scanner(System.in);
		int n = scan.nextInt();
		long[] str = new long[n];
		for (int i = 0; i < n; i++) {
			str[i] = scan.nextLong();
		}
		Arrays.sort(str);
		long sq = 1;
		int count = 0;
		for (int i = n - 1; i > 0; i--) {
			if (str[i] == str[i - 1]) {
				sq = sq * str[i];
				i--;
				count++;
				if (count >= 2) {
					break;
				}
			}

		}
		if (count < 2) {
			System.out.println(0);
		} else {
			System.out.println(sq);
		}

	}
}