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);
        
        int N = sc.nextInt();
        int[] A = new int[N];
        for(int i = 0; i < N; i++){
            A[i] = sc.nextInt();
        }
        sc.close();

        Arrays.sort(A);
        long h = 0;
        long w = 0;

        int count = 0;

        int idx = N-1;
        while(idx > 0){
            if(A[idx] == A[idx-1]){
                if(count == 1){
                    w = A[idx];
                    count++;
                }
                if(count == 0){
                    h = A[idx];
                    count++;
                } 
                idx--;
            }
            idx--;
        }
        System.out.println(h*w);
    }
}