int main(){
	int N;
	cin>>N;
	double m=0; 
	if(N<=150){
	m=N*0.4463;
	}
    if(N>150&&N<=400){
	m=150*0.4463+(N-150)*0.4663;
	}
	else{
	m=150*0.4463+250*0.4663+(N-400)*0.5663;
	}cout<<floor(m*10+0.5)/10.0;	
# }