#include <iostream>
#include <iomanip>
using namespace std;

int main() {
	int n;
	double money;
	cin >> n;

	if (n <= 150) {
		money = (double)n * 0.4463;
	} else if (n > 150 && n <= 400) {
		money = 150 * 0.4463 + (n - 150) * 0.4663;
	} else {
		money = 150 * 0.4463 + 250 * 0.4663 + (n - 400) * 0.5663;
	}

	cout << fixed << setprecision(1);
	cout << money;
	return 0;
}