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