// editor1
#include<iostream>
using namespace std;
class Customer{
    public:
    void cName(string name){
        cout<<name<<" ";
        
    }
};
class Meter{
    public:
    int units(int unit){
        return unit;
    }
};
class billl: public Customer ,public Meter{
    public :
    void total(int u){
        int unit = units(u);
        int t = unit*5 + 50;
        cout<<t<<endl;
    }
};
int main(){
    string nmae;
    int units;
    cin>>name>>units;
    if(unit<0){
        cout<<"Invalid input";
        return 0;
    }
}