#include<bits/stdc++.h>
int main(){
	double n,ans=0.2;
	scanf("%lf",&n);
	if(n>30){
		printf("Fail");
		return 0;
	}
	else if(n<=10){
		ans+=n*0.8;
	}
	else if(n>10&&n<=20){
		ans+=8+(n-10)*0.75;
	}
	else{
		ans+=8+7.5+(n-20)*0.7;
	}
	printf("%.2f",ans);
	return 0;
}