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;
typedef long long ll;



int main()
{
  set<int> s;
  int m1=0, m2=0;
  int n;cin>>n;
  for(int i=0;i<n;i++)
    {
      int a;cin>>a;
      if(s.find(a)==s.end())
	s.insert(a);
      else if(a>m2)
	{
	  s.erase(a);
	  m2=m1;
	  m1=max(a,m1);
	  m2=min(m2,a);
	}
    }
  printf("%lld\n",(long long)m1*(long long)m2);
  return 0;
}
