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>
#include<queue>
using namespace std;
int n,a[100000+5];
int main()
{
	priority_queue<int> pq;
	cin>>n;
	for(int i=1;i<=n;i++)
	{
		cin>>a[i];
	}
	sort(a+1,a+n+1);
	for(int i=1;i<=n;i++)
	{
		if(a[i]==a[i+1])
		{
			pq.push(a[i]);
			i++;
		}
	}
	if(pq.size()<=1)
	{
		cout<<0;
	}
	else
	{
		long long int ans=1;
		for(int i=1;i<=2;i++)
		{
			ans*=pq.top();
			pq.pop();
		}
		cout<<ans;
	}
	return 0;
}