#include <bits/stdc++.h>
using namespace std;
int main(){
	int x;
	cin>>x;
	double price=0;
	if(x>30){
		cout<<"Fail";
		return 0;
	}
	if(x<=10) price= x*0.8;
	else if(x<=20)  price=(x-10)*0.75+8;
	else if(x<=30)  price=(x-20)*0.7+8+7.5;   
	cout<<fixed<<setprecision(2)<<price+0.2;
	return 0;
}