#include<bits/stdc++.h>
using namespace std;
int main(){
	int a;
	double b;
	cin>>a;
	b=(150<a?150:a)*0.4463;
		if(a>150&&a<=400){
			b+=(400<a?400-151:a-150)*0.4663;
				}if(a>400){
					b=+(a-400)*0.5663;
				}
	cout<<setprecision(1)<<fixed<<b<<endl;
}