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 n,a[100005],x=0,y=0,b;
int main() 
{
	ios::sync_with_stdio(false);
	cin>>n;
	for(int i=0;i<n;i++)
		cin>>a[i];    
	sort(a,a+n);
	reverse(a,a+n);
	for(int i=0;i<n;i++)
	{
		if(a[i]==a[i+1])
		{
			if(x<y)
			{
				x=a[i];
				i++;			
			}    
			else
			    y=a[i];
			i++;
		}
		if(x!=0 and y!=0)
		    break;
	}
	cout<<(long long)(x)*y;
	return 0;
}