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) {
	Main m = new Main();
	m.answer();
    }

    private Scanner scan = new Scanner(System.in);
    private final int N;
    private final int[] A;

    public Main() {
	N = Integer.parseInt(scan.next());
	A = new int[N];
	
	for (int i = 0; i < N; i++) {
	    A[i] = Integer.parseInt(scan.next());
	}

	scan.close();
    }

    public final void answer() {
	Arrays.sort(A);

	int h = 0;
	int w = 0;
	for (int i = N-1; i > 0; i--) {
	    if(A[i] == A[i-1]) {
		if(h == 0) {
		    h = A[i];
		    i--;
		} else if(w == 0) {
		    w = A[i];
		    break;
		}
	    }
	}
	System.out.println((long)h * w);
    }
}
