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){
        Scanner sc = new Scanner(System.in);
        long N = sc.nextLong();
        Map<Long, Long> l = new HashMap<>();
        for(int i = 0;i < N;i++){
            long a = sc.nextLong();
            if(l.containsKey(a))    l.put(a, l.get(a)+1);
            else    l.put(a, (long)1);
        }
        long m1 = 0;
        long m2 = 0;
        for(Long key : l.keySet()){
            long value = l.get(key);
            if(key > m1){
                if(value >= 4){
                    m1 = key;
                    m2 = key;
                }else if(value >= 2){
                    m2 = m1;
                    m1 = key;
                }
            }else if(key > m2 && value >= 2){
                m2 = key;
            }
        }
        System.out.println(m1*m2);
    }
}