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;
long long int a[100100], i, n, temp, width, height;
int main()
{
    cin >> n;
    for(i=0;i<n;i++)
        cin >> a[i];
    sort(a, a+n);
    for(i=0;i<n-1;i++)
    {
        if(a[i]==a[i+1])
        {
            temp = height;
            height = a[i+1];
            width = temp;
            i++;
        }
    }
    cout << height*width<< endl;
}
