#include<iostream>
  
using namespace std;
  
int main(){
  
	double a;
	cin>>a;
	if(a<=150 && a>0){
		printf("%.1lf",a*0.4463);
	}
	if(a>=151 && a<=400){
		printf("%.1lf",0.4663*a);
	}
	if(a>=401){
		printf("%.1lf",0.5663*a);
	}
}