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;
  cin>>n;
  vector<int>v(n);
  for(int i=0;i<n;i++)cin>>v[i];
  sort(v.begin(),v.end());
  
  long long a=0,b=0;
  
  for(int i=n-1;i>=1;i--){
    if(v[i]==v[i-1]){
      if(a==0)a=v[i];
      else if(b==0)b=v[i];
      else break;
      i--;
    }
  }
  cout<<a*b<<endl;
}
