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.HashMap;
import java.util.Scanner;

public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner((System.in));
		int N = sc.nextInt();
		HashMap<Integer, Integer> a = new HashMap<Integer, Integer>();
		long x = 0, y = 0, ans = 0;

		for (int i = 0; i < N; i++) {
			int b = sc.nextInt();
			int c = a.get(b) == null ? 0 : a.get(b);
			a.put(b, (c + 1));
			if (a.get(b) == 2) {
				if (y <= x && x <= b) {
					y = x;
					x = b;
					a.put(b, 0);
				} else if (y <= x && y <= b && b <= x) {
					y = b;
					a.put(b, 0);

				}
			}
		}

		ans = x * y;
		
		System.out.println(ans);

		sc.close();
	}
}