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();
  Map<Integer,Integer>map=new HashMap<>();
  for(int i=0;i<n;i++){
    int po=sc.nextInt();
  if(map.containsKey(po)){
    map.put(po,map.get(po)+1);
  }
    else map.put(po,1);
  }
  ArrayList<Integer>a=new ArrayList<>();
  for(Integer i:map.keySet())a.add(i);
  Collections.sort(a);
  int count=a.size()-1;
  int x=0,y=0;
  while(count!=-1){
    if(map.get(a.get(count)).compareTo(2)>=0){
    x=a.get(count);
      map.put(a.get(count),map.get(a.get(count))-2);
      break;
    }
    else count--;
  }
  while(count!=-1){
    if(map.get(a.get(count)).compareTo(2)>=0){
    y=a.get(count);
      map.put(a.get(count),map.get(a.get(count))-2);
      break;
    }
    else count--;
  }
  System.out.println((long)x*y);
}
}
