#include<bits/stdc++.h>
using namespace std;
double all,b=0.4463,c=0.4663,d=0.5663;
int main(){
	cin>>all;
	if(all<=150){
		double n=b*all;
		cout<<fixed<<setprecision(1)<<n;
	}
	else if(all>=151&&all<=400){
		double m=c*all;
		cout<<fixed<<setprecision(1)<<m;
	}
	else if(all>=401){
		double g=d*all;
		cout<<fixed<<setprecision(1)<<g;
	}
	return 0;
}