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<cstdio>
#include<functional>
#include<algorithm>
using namespace std;
int main(void)
{
	int i,j,n,a[100000],cnt,x[2];
	long long s;
	scanf("%d",&n);
	for(i=0;i<n;i++)	scanf("%d",&a[i]);
	sort(a,a+n);
	cnt=0;
	for(i=n-1;i>=1;i--)	{
		if(a[i]==a[i-1])	{
			x[cnt]=a[i];
			i--;
			cnt++;
			if(cnt==2)	break;
		}
	}
	if(cnt!=2)	s=0;
	else s=(long long)x[0]*x[1];
	printf("%lld\n",s);
    return 0;
}