#include<iostream>
using namespace std;

int main()
{
	int n;
	cin >> n;
	double m = 0;
	if(n <= 150) m = 0.4463 * n;
	else if(n >= 151 && n <= 400) m = 0.4663 * n;
	else m = n * 0.5663;
	cout << m << endl;
	return 0;
}