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>
using namespace std;
#include <queue>
#include <algorithm>

int main()
{
	int s;
	cin>>s;
	long long a[s+1];
	for(int i=0;i<s;i++)
	{
		cin>>a[i];
	}
	sort(a,a+s);
	long long k=0,max1=-11111,max2=-11111;
	while(k<s)
	{
		if(a[k]==a[k+1]) {
			max2=max1;
			max1=a[k];
			k+=2;
		}
		else
			k++;
	}
	if(max1!=-11111&&max2!=-11111) cout<<max1*max2;
	else cout<<0;
	return 0;
}