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()
{
	int n, a[100000];
	long long b = 0, c = 0;
	cin >> n;
	
	for (int i = 0; i < n; i++)
		cin >> a[i];
		
	sort(a, a+n);
	
	for (int i = 0; i < n-1; i++)
		if (a[i] == a[i+1])
		{
			if (a[i] > c)
			{
				b = c;
				c = a[i];
			}
			else if (a[i] > b)
				b = a[i];
			
			i++;
		}
		
	cout << b * c;
}