#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;

}