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<algorithm>
#include<functional>

using namespace std;
int main(void)
{
	long long int a[100000],i,n,w,x,y;
	scanf("%lld",&n);
	for(i=0;i<n;i++) scanf("%lld",&a[i]);
	sort(a,a+n,greater<int>());
	x=0; y=0;
	for(i=0;i<n;i++){
		if(x==0){
			if(a[i]==a[i+1]){
				x=a[i]; i++;
			}
		}
		else{
			if(a[i]==a[i+1]){
				y=a[i]; break;
			}
		}
	}
	if(y==0) printf("0\n");
	else printf("%lld\n",x*y);	
	return 0;
}