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 a[100005];
int main()
{
    int n;
    cin >> n;
    for(int i = 0;i < n;i++)cin >> a[i];
    sort(a,a+n);
    long long a1 = 0,a2 = 0;
    for(int i = n-1;i>0;i--)
    {
        if(a[i] == a[i-1])
        {
            if(a1 == 0)a1 = a[i];
            else {a2 = a[i];break;}
            i--;
        }
    }
    if(a1&&a2)cout << a1*a2;
    else cout << 0;
    return 0;
}
