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.Scanner;
import java.util.TreeMap;

public class Main {

	public static void main(String[] args) {
		try (Scanner sc = new Scanner(System.in)) {
			int n = sc.nextInt();
			TreeMap<Long, Long> map = new TreeMap<Long, Long>();

			for (long i = 0; i < n; i++) {
				long a = sc.nextLong();
				if (map.keySet().contains(a)) {
					map.put(a, map.get(a)+ 1);
				} else {
					map.put(a, 1l);
				}
			}

			int count = 0;
			long result = 1l;
			Long[] tmp = map.keySet().toArray(new Long[map.size()]);

			for (int i = tmp.length - 1; 0 <= i; i--){
				if (2 <= map.get(tmp[i])) {
					if (count == 0 && 4 <= map.get(tmp[i])) {
						System.out.println(tmp[i] * tmp[i]);
						return;
					}
					result *= tmp[i];
					count++;
					if (count == 2) {
						System.out.println(result);
						return;
					}
				}
			}
			System.out.println(0);
		}
	}
}
