#include <bits/stdc++.h>
using namespace std;
int main() {
	int a;
	cin >> a;
	if (a <= 10) {
		cout << fixed << setprecision(2) << a * 0.8+0.2;
	} else if (a > 10 && a <= 20) {
		cout << fixed << setprecision(2) << (a-10) * 0.75 +10*0.8+0.2;
	} else if (a > 20 && a <= 30) {
		cout << fixed << setprecision(2) << (a-20)*0.7+10*0.75+10*0.8+0.2;
	} else {
		cout << "Fail";
	}
	return 0;
}