#include<bits/stdc++.h> using namespace std; int main(){

double x;
cin>>x;
if      (x<=10) printf("%.2lf",x*0.8+0.2);
else if (x<=20) printf("%.2lf",8+(x-10)*0.75+0.2);
else if (x<=30) printf("%.2lf",15.5+(x-20)*0.7+0.2);
else cout <<"Fail";

return 0;

}

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

#include<bits/stdc++.h> using namespace std; int main() { double a; cin>>a; if(a<=10) { cout<<fixed<<setprecision(2)<<a0.8+0.2; } if(a<=20&&a>10) { cout<<fixed<<setprecision(2)<<(a-10)0.75+100.8+0.2; } if(a<=30&&a>20) { cout<<fixed<<setprecision(2)<<100.8+10*0.75+(a-20)*0.7+0.2; } if(a>30) { cout<<"Fail"; } return 0; }

#include<bits/stdc++.h>
using namespace std;
int main()
{
	int n;
	cin>>n;
	if(n<=10){
		cout<<fixed<<setprecision(2)<<n*0.8+0.2;
	}
	if(n>10&&n<=20){
		n=n-10;
		cout<<fixed<<setprecision(2)<<n*0.75+8.2;
	}
	if(n>20&&n<=30){
		n=n-20;
		cout<<fixed<<setprecision(2)<<n*0.7+15.7;
	}
	if(n>30){
		cout<<"Fail";
	}
	return 0;
}