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[] sticks = new int[N];
        
        for(int i = 0;i < N;i++){
            sticks[i] = sc.nextInt();
        }
        
        Arrays.sort(sticks);
                
        System.out.println(makeRectangle(sticks));
        
    }    
    
    static long makeRectangle(int[] sticks){
         
        int a = 0;
        int b = 0;
        int prev = -1; 
       
        for(int i = sticks.length - 1;i >= 0;i--){
            if(prev == sticks[i]){
                  if(a == 0){
                      a = sticks[i];
                      prev = -1;
                      continue;
                  }else{
                     b = sticks[i];
                     break;
                  }                
            }            
            prev = sticks[i];
        }
        
        return (long) a*b;
    }    
    
}       
