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 arr[200000];
int main()
{
  long long   int n,b=0,c=0,a,f=0;
    cin>>n;
    for(int i=0;i<n;i++)
    {
        cin>>arr[i];
    }
    sort(arr,arr+n);
    for(int i=n-2;i>=0;i--)
    {
        if(arr[i]==arr[i+1]&&f==0){b=arr[i];f=1; i--;}
        else if(arr[i]==arr[i+1]&&f==1){c=arr[i];break;}
    }
    a=b*c;
    cout<<a<<endl;
}
