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;
int N_MAX = 100000;
int main()
{
  int n,i;
  long long t=0,res=0;
  long long a[N_MAX];
  cin >> n;
  for(i=0;i<n;i++)
    cin >> a[i];
  sort(a,a+n,greater<long long>());
  for(i=1;i<n;i++)
    if(a[i]==a[i-1])
      if(t==0){
        t=a[i];
        i++;
      }else{
        res=a[i]*t;
        break;
      }
  cout << res << endl;
  return 0;
}