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 reader = new Scanner(System.in);
		int N = reader.nextInt();
		long[] arr = new long[N];
		long X = 0;
		long Y = 0;
		for (int i = 0; i < N; i++) {
			arr[i] = reader.nextLong();
		}
		Arrays.sort(arr);
		for (int i = N-1; i > 0; i--) {
			if (X == 0 && arr[i] == arr[i-1]) {
				X = arr[i];
				i--;
			}
			else if (X != 0 && arr[i] == arr[i-1]) {
				Y = arr[i];
				break;
			}
		}

		System.out.println(X*Y);
		reader.close();
	}


}



