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 n, a[100010];

int main() {
	cin >> n;
	for (int i = 0; i < n; i++) {
		cin >> a[i];
	}
	sort(a, a + n);
	long long ans_1 = 0, ans_2 = 0;
	for (int i = 0; i < n - 1; i++) {
		if (a[i] == a[i + 1]) {
			ans_2 = ans_1;
			ans_1 = a[i];
			if (i != n - 2)
				i += 1;
		}
	}
	cout << ans_1 * ans_2 << endl;
	return 0;
}