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();
        long[] nums=new long[n];
        for(int i=0;i<n;i++){
            nums[i]=sc.nextInt();
        }
        Arrays.sort(nums);
        int count=0;
        long ans=1;
        for(int i=n-1;i>0;i--){
            if(count==0&&nums[i]==nums[i-1]){
                ans=nums[i];
                count++;
                i--;
            }else if(count==1&&nums[i]==nums[i-1]){
                System.out.println(ans*nums[i]);
                return;
            }
        }
        System.out.println(0);
    }
}