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 <algorithm>
using namespace std;
int a[100000+100];
int n;
int main() {	
	cin>>n;
	for (int i = 1; i <= n; i++) {
		cin >> a[i];
	}
	sort(a+1, a+1+n); 
	
	long long s = 1;
	int num = 0;
	for (int i=n; i >= 2; i--) {
		if (a[i] == a[i-1]) {
			s = s*a[i];
			num = num+1;
			i--;
		}
		if (num==2) {
			break;
		}
	}
	if (num == 2) {
		cout<<s<<endl;
	}else {
		cout<<0<<endl;
	}
	return 0;
}
