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.HashMap;
import java.util.Scanner;

class Main {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        HashMap<Integer, Integer> map = new HashMap<>();
        int n = in.nextInt();
        for(int i = 0; i < n; i++) {
            int a = in.nextInt();
            if(map.containsKey(a)) {
                map.put(a, map.get(a) + 1);
            }else {
                map.put(a, 1);
            }
        }
        Object[] list = (Object[])(map.keySet().stream().filter(m -> map.get(m) > 1).toArray());
        Arrays.sort(list);
        if(list.length > 1) {
            int a = (Integer)(list[list.length - 1]);
            int b = (Integer)(list[list.length - 2]);
            if(map.get(list[list.length - 1]) > 3) {
                System.out.println((long)a * (long)a);
            } else {
                System.out.println((long)a * (long)b);
            }
        }else {
            System.out.println(0);
        }
    }
}
