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;
long long a[100001],n,t1,t2,f=1,t3;
int main()
{
	cin>>n;
	for(int i=1;i<=n;i++)	cin>>a[i];
	sort(a+1,a+n+1);
	for(int i=n;i>=1;i--)
	{
		if(a[i]==a[i-1]&&f==0)
		{
			t2=a[i];
			break;
		}
		if(a[i]==a[i-1]&&f==1)
		{
			t1=a[i];
			i--;
			f=0;
		}
	}
	cout<<t1*t2; 
}	
