#include<bits/stdc++.h>
using namespace std;
int main(){
	int a;
	cin>>a;
	double ans;
	if(a<=150) ans=0.4463*a;
	if(a>150&&a<=400) ans=0.4463*150+0.4663*(a-150);
	else ans=ans=0.4463*150+0.4663*250+0.5663*(a-400);
	cout<<fixed<<setprecision(1)<<ans;
}