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.*;

public class Main {
    public static void main(String[] args) throws Exception {
        // Your code here!
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        Set<Integer> set = new HashSet<Integer>();
        List<Integer> list = new ArrayList<Integer>();
        
        while (n-- > 0) {
            int num = sc.nextInt();
            if (set.contains(num)) {
                list.add(num);
                set.remove(num);
            } else {
                set.add(num);
            }
            
        }
        if (list.size() < 2) {
            System.out.println("0");
            return;
        }
        list.sort(Comparator.reverseOrder());
        
        long answer = (long)list.get(0) * list.get(1);
        
        System.out.println(answer);
    }
}