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.*;
class Main
{
    public static void main (String[] args)
    {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        long[] a = new long[n];
        for(int i = 0; i < n; i++) a[i] = sc.nextInt();
        Arrays.sort(a);
        long max1 = 0, max2 = 0;
        int i = n-1;
        while(max2 == 0 && i > 0){
            if(a[i] == a[i-1]){
                if(max1 == 0) max1 = a[i];
                else max2 = a[i];
                i--;
            }
            i--;
        }
        System.out.println(max1 * max2);
    }
}