#include <iostream>
#include <iomanip>
using namespace std; 
int a;
double b=0;
int main(){
    cin>>a;
    if(a>=150){
        b+=150*0.4463;
        if(a>=400){
            b+=250*0.4663;
            b+(a-400)*0.5663;
        }else{
            b+=(a-150)*0.4664;
        }
    }else{
        b+=a*0.4463;
    }
    cout<<fixed<<setprecision(1)<<b;
}