int main(){
int y;
double d,yi=150*0.4463,er=(400-150)*0.4663;
scanf("%d",&y);
if(y<=150) d=y*0.4463;
else if(150<y<=400){
	d=(y-150)*0.4663;
	d=yi+d;
}
else{
	d=yi+er+(y-400)*0.5663;
}
d=int((d*10)+0.5)/10.0;
printf("%0.1f",d);
	return 0;
}