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 <math.h>
#include <algorithm>
#include <string>
#include <string.h>
using namespace std;

int main() {
	long long int hen=0,maxsq=0,t=0,y=0,maxty=0,c=1,ans=0,N,A[100000]={};
	cin>>N;
	for(int i=0;i<N;i++)
	{
		cin>>A[i];
	}
	sort(A,A+N);
	for(int i=0;i<N-1;i++)
	{
		if(A[i]!=A[i+1])c=1;
		if(A[i]==A[i+1])c++;
		if(c==2)
		{
			y=t;
			t=A[i];
		}
		if(c>3)hen=A[i];
	}
	ans=max(y*t,hen*hen);
	cout<<ans;
}
