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;
int main()
{	
int n;    
int A[100100];	
vector<long long> v;
cin >> n;	
for(int i=0;i<n;i++)
{		
cin >> A[i];	
}	
sort(A,A+n);
reverse(A,A+n);	
for(int i=1;i<n;i++)
{		
if(A[i-1]==A[i])
{			
v.push_back(A[i]);
i++;		
}		
if(v.size()==2)
{			
cout << v[0]*v[1] << endl;			
return 0;		
}	
}		
cout << 0 << endl;	
return 0;
}



