#include<stdio.h>
int main()
{
	int a; 
	double b;
	scanf("%d",&a);
	if(a<=150)
	{
		b=a*0.4463;
		printf("%.1lf",b);
	}
	if(a>=151&&a<=400)
	{
		b=(a-150)*0.4663+150*0.4463;
		printf("%.1lf",b);
	 } 
	 if(a>=401)
	 {
	 	b=150*0.4463+249*0.4663+(a-400)*0.5663;
	 	printf("%.1lf",b);
	 }
	return 0;
 }