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()
{
  vector<long int> v;
  long int n;
  scanf("%ld",&n);
  long int a[n],i;
  for(i=0;i<n;++i)
       scanf("%ld",&a[i]);
  
  sort(a,a+n);
  for(i=0;i<n-1;++i)
  {
    if(a[i]==a[i+1])
    {
      v.push_back(a[i]);
      i+=1;
    }
  }
  
  if(v.size()<2)
      printf("0");
  
  else
     printf("%ld",v[v.size()-1]*v[v.size()-2]);
}