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<long long> a(n);
  for(int i=0; i<n; i++)cin>>a.at(i);

  sort(a.begin(), a.end());

  long long x=0, y=0;
  int z=0;
  for(int i=n-1; i>0; i--){
    if(a.at(i)==a.at(i-1)){
      x=a.at(i);
      z=i-1;
      break;
    }
  }
  for(int i=z-1; i>0; i--){
    if(a.at(i)==a.at(i-1)){
      y=a.at(i);
      break;
    }
  }

  cout<<x*y<<endl;
}