#include<iostream>
using namespace std;
double i,sum;
int main()
{
	cin>>i;
	if(i<=150)
	{
		sum=i*0.4463;
		printf("%.1f",sum);
	}
	else if(i>=151&&i<=400)
	{
		sum=150*0.4463+(i-150)*0.4663;
		printf("%.1f",sum);
	}
	else
	{
		sum=150*0.4463+400*0.4663+(i-400)*0.5663;
		printf("%.1f",sum);
	}
	return 0;
}