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>
long long n, m, s, a[100005];
int main() {
	int i;
	scanf("%lld", &n);
	for(i=0; i<n; i++) scanf("%lld", &a[i]);
	std::sort(a, a+n);
	for(i=n-1; i; i--) {
		if(a[i]==a[i-1]) {
			if(m==0) m = a[i];
			else {s = m*a[i]; break;}
			i--;
		}
	}
	printf("%lld", s);
	return 0;
}