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;
vector <long long> v;
long long a=1,b; 
int main()
{
	int n,i,j=0;
	scanf("%d",&n);
	for(i=0;i<n;i++)
	{
		cin >> b;
		v.push_back(b);
	}
	sort(v.begin(),v.end(),greater<int>());
	
	for(i=0;i<v.size();i++)
	{
		if(v[i]==v[i-1])
		{
			++j;
		a*=v[i];
		if(j==2) break;
		++i;
}
	}
	if(j==2) 
	cout << a;
	else
	cout << 0;
}