#include<iostream>

using namespace std;

int main()

{

	int df;
  
	double m;
  
	cin>>df;
  
	if(df<=150)
  
	{
  
		m=df*0.4463;
    
	}
  
	else if((df>=151)&&(df<=400))
  
	{
  
		m=(df-150)*0.4663+150*0.4463;
    
	}
  
	else if((df>=401))
  
	{
  
		m=(df-400)*0.5663;
    
		m=m+150*0.4463+(400-150)*0.4663;
    
}

	m=int(m*10+0.5)/10.0;
  
	cout<<m;
  
	return 0;
  
}