#include<bits/stdc++.h>
using namespace std;
int a;
int main()
{
	cin>>a;
	if(a<=150)
		cout<<fixed<<setprecision(1)<<a*0.4463<<endl;
	else if(a>150&&a<=400)
			cout<<fixed<<setprecision(1)<<a*0.4663<<endl;
		    else
			  	cout<<fixed<<setprecision(1)<<a*0.5663<<endl;			   	
	return 0;
}