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