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 n;
long long a[1000010];

int main()
{
	cin>>n;
	long long i,j;
	for (i=1;i<=n;i++)cin>>a[i];
	sort(a+1,a+n+1);
	i=n;
	long long x=-100,y=-100;
	for (i=n;i>=1;i--)
		if (a[i]==a[i-1]){
			x=a[i];
			break;
		}
	for (i-=2;i>=1;i--)
		if (a[i]==a[i-1]){
			y=a[i];
			break;
		}
	if (x==-100 || y==-100)
		cout<<0<<endl;
	else 
		cout<<x*y<<endl;
	return 0;
}