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 main()
{
	int n;
	cin>>n;
	int i;
	int count=1;
	long long max1=0,max2=0;
	long long a[100000];
	for(int i=0;i<n;i++)
	{
		cin>>a[i];
	}
	sort(a,a+n);
	for(i=0;i<n;i++)
	{
		if(a[i]==a[i+1])
		{
			count=2;
		}else
		{
			count=1;
		}
		if(count>=2)
		{
			max1=max2;
			max2=a[i];
			i++;
			count=1;
		}
	}
	cout<<max1*max2<<endl;
}