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.io.IOException;
import java.util.Arrays;
import java.util.Scanner;

public class Main {

	public static void main(String[] args) throws NumberFormatException, IOException {

		Scanner sc = new Scanner(System.in);

		int N = sc.nextInt();
		int[]A;
		A = new int[N];
		int len1 =0;
		int len2 =0;

		for (int i=0; i<N; i++){
			A[i] = sc.nextInt();
		}
		Arrays.sort(A);
		for (int i=N-2; i>=0 ;i--){
			if (A[i] == A[i+1]){
				if (len1 == 0){
					len1 = A[i];
					if (i-2 >= 0 && A[i-1]==len1 && A[i-2]==len1){
						len2 = len1;
						break;
					}
				} else {
					if (len1 != A[i]){
						len2 = A[i];
						break;
					}
				}
			}
		}
		System.out.println((long)len1 * (long)len2);
	}
}

