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;
long long n,ma,se,a[100100];
int main()
{
	cin>>n;
	for(int i=0;i<n;i++)
		cin>>a[i];
	sort(a,a+n,greater<int>());
	for(int i=0;i<n;i++)
	{
		if(a[i]==a[i+1])
		{
			if(ma==0)
				ma=a[i];
			else
				se=a[i];
			i++;		
		}
		if(ma!=0 && se!=0)
			break;
	}		
	cout<<ma*se<<endl;
} 