#include<iostream>
#include<string>
using namespace std;
class Customer
{
    protected:
    string customer;
    public:
    void cname()
    {
        cin>>customer;
    }
};
class Meter
{
    protected:
    int units;
    public:
    void cunits()
    {
        cin>>units;
    }
};
class totalbill : public customer, public meter
{
    public:
    void pro()
    {
        if(units<0)
        {
            cout<<"Invalid"<<endl;
        }
        else
        {
            int total = (units*5)+50
        }
    }
};
int main()
{
    totalbill pro;
    pro.cname();
    pro.cunits();
    pro.pro();
}