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;

typedef long long ll;

int main(){
  int n;
  cin >> n;
  ll a[n];
  for(int i=0;i<n;i++){
    cin >> a[i];
  }
  sort(a,a+n);
  ll x=0,y=0;
  int k;
  for(int i=n-1;i>-1;i--){
    if(a[i]==a[i-1]){
      x=a[i];
      k=i-1;
      break;
    }
  }
  for(int i=k-1;i>-1;i--){
    if(a[i]==a[i-1]){
      y=a[i];
      break;
    }
  }
  cout << x*y << endl;
}
  
