#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;

}