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 scn = new Scanner(System.in);
		int N = scn.nextInt();
		long[] A = new long[N];
		for(int i = 0;i < N;i++) {
			A[i] = scn.nextLong();
		}
		Arrays.sort(A);
		int count = 0;
		long buf = 0;
		long a = 0,b = 0;
		for(int i = N-1;i > -1;i--) {
			if(buf == A[i]) {
				count ++;
			}else {
				buf = A[i];
				count = 1;
			}

			if(count == 2) {
				if(a!=0) {
					b = buf;
					break;
				}else {
					a = buf;
					count = 0;
				}
			}
		}
		System.out.println(a*b);
	}

}
