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 <bits/stdc++.h>
using namespace std;



int main()
{
	int n;
	cin >> n;
	vector<long long> a(n);
	for (int i = 0; i < n; i++) {
		cin >> a[i];
	}
	sort(a.begin(), a.end(), greater<long long>());
	vector<long long> p;
	for (int i = 0; i < n - 1; i++) {
		if (a[i] == a[i + 1]) {
			p.push_back(a[i]);
			i++;
		}
		if (p.size() == 2) {
			cout << p[0] * p[1] << endl;
			return 0;
		}
		
	}
	cout << 0 << endl;
	return 0;
}

