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 = Integer.parseInt(sc.next());
        HashMap<Integer, Integer> map = new HashMap<Integer, Integer>();
        int ans = 0;
        for(int i=0;i<n;i++){
            int num = Integer.parseInt(sc.next());
            map.put(num, map.containsKey(num)?map.get(num)+1: 1);
        }
        long a=0l,b=0l;
        for(int i: map.keySet()){
            if(map.get(i)>1){
                if(map.get(i)<4){
                    if(a<=i){
                        b=a;
                        a=i;
                    }else if(b<i){
                        b = i;
                    }
                }else{
                    if(a<=i){
                        b=i;
                        a=i;
                    }else if(b<i){
                        b = i;
                    }
                }
            }
        }
        System.out.println(a*b);
    }
}
