#include<bits/stdc++.h>
using namespace std;
int main(){
double a,b;
cin>>a;
if (a<=150)
b=a*0.4463;
else if(150<a<=400)
b=150*0.4463+(a-150)*0.4663;
else if(a>400)
b=150*0.4463+250*0.4663+(a-400)*0.5663;
cout<<fixed<<setprecision(1)<<b<<endl;
return 0;
}