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 <cstdlib>
#include <map>
using namespace std;

int main()
{
	long long int N,a = 0,b = 0;
	map<int,int>mp;

	cin >> N;

	for (int i = 0; i < N; i++) {
		int m;
		cin >> m;
		mp[m]++;
		if (mp[m] % 2 == 0) {
			int k = 0;
			abs(m + a) < abs(m + b) ? k = 1 : k = 2;
			if (k == 1 && m > a)a = m;
			if (k == 2 && m > b)b = m;
		}
	}

	cout << a*b;

	return 0;
}