#include<iostream>
using namespace std;
class Customer{
    protected:
    string name,password;
    public:
    void display(){
        cin >> name>>password;
    }

class Meter{
    protected: 
    string role;
    public:
    void display1(){
        cin>>role;}};
        class bill: public meter, public customer{
            public:
            void result(){
              if (name.empty()||password.empty()||role.empty()){
                  cout<<name<<endl<<role;
            
        }
    }
        
    
    
        
};
int main()
{
    bill b;
    b.display();
    b.display();
    b.result();
    return 0;
}