#include<bits/stdc++.h>
using namespace std;
unsigned int a=0.4463,b=0.4663,c=0.5663,d,e,f,n,s;
int main(){
    cin>>n;
    if(n<=150){
        d=a*n;
        cout<<setprecision(2)<<fixed<<d<<endl;
        return 0;
    }else{
    if(n>150&&n<=400){
        e=d+(n-150)*b;
        cout<<setprecision(2)<<fixed<<e<<endl;
        return 0;
    }else{
    if(n>400)
        f=e+(n-400)*c;
        cout<<setprecision(2)<<fixed<<f<<endl;
    }
    return 0;
}
}