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 <iostream>
#include <algorithm>
using namespace std;
int main(void){
  int n;
  cin >> n;
  unsigned int a[100001]={};
  for(int i=0; i<n; i++){
    cin >> a[i];
  }
  sort(a, a+n);
  reverse(a, a+n);
  long long int x[2]={};
  int k=0;
  for(int i=1; i<n; i++){
    if(a[i-1]==a[i]){
      x[k]=a[i];
      if(x[1]!=0){
        break;
      }
      k++;
      i++;
    }
  }
  cout << x[0]*x[1] << endl;
  return 0;


}
