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()
{
    long long int n,i,j;
    cin>>n;
    long long int a[n];
    long long int fre[2] = {0};
    for(i=0;i<n;i++)
    {
        cin>>a[i];
    }
    sort(a,a+n);
    for(i=n-1,j=0;i>=0,j<2;i--)
    {
        if(a[i+1]==a[i])
            fre[j++] = a[i--];
    }
    cout<<fre[0]*fre[1]<<endl;
}
