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
#include<bits/stdc++.h>
using namespace std;
int main(){
  int n;
  long long x=-1,y=-1;
  int a[100009];
  cin>>n;
  for(int i=0;i<n;i++)cin>>a[i];
  sort(a,a+n);
  reverse(a,a+n);
  for(int i=0;i<n-1;i++){
    if(a[i]==a[i+1]){
      if(x==-1){
	x=a[i];
      }
      else if(y==-1){
	y=a[i];
      }
      i++;
    }
  }
  if(x==-1&&y==-1)cout<<0<<endl;
  else cout<<x*y<<endl;
  return(0);
}
