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 <vector>
#include <algorithm>
using namespace std;

int main()
{
	int n;
	cin >> n;
	auto a = vector<int>(n);
	for(auto&& aa : a) cin >> aa;
	sort(a.begin(), a.end());
	long long int s = 0, t = 0;
	int p = n - 1;
	while(p > 0 && s * t == 0){
		if(a[p] == a[p - 1]){
			if(s == 0) s = a[p];
			else t = a[p];
			--p;
		}
		--p;
	}
	cout << s * t << endl;
	return 0;
}