#include<iostream> 
#include<cstring>
//#include<cmath>
//#include<algorithm>
//#include<iomanip>  cout<<fixed<<setprecision()
using namespace std;

int main(){
	int a;double n;
	cin>>a;
	if(a<=0){
		cout<<0;
		return 0;
	}
	if(a<=150){
		n+=a*0.4463;
		printf("%.1lf",n);
	}else if(a>=151 && a<=400){
		n+=0.4463*150;
		n+=(a-150)*0.4663;
		printf("%.1lf",n);
	}else if(a>401){
		n=0.4463*150+249*0.4663+(a-401)*0.5663;
		printf("%.1lf",n);
	}
	
	return 0;
}