Inheritance

#include<iostream.h>
#include<conio.h>
 #include<stdio.h>
 class common
 {
 int rl,ph;
 char na[30];
 public:
 void getdata()
 {
 cout<<"\nEnter the name ";
 gets(na);
 cout<<"\nEnter the ID";
 cin>>rl;
 cout<<"\nEnter the phone no ";
 cin>>ph;
 }
 void showdata()
 {
 cout<<"\nThe details are=\n"<<na<<"\n"<<rl<<"\n"<<ph;
 }
 };

 class education
 {
 char uni[20];
 char sess[10];
 char res[10];
 public:
 void getmarks()
 {
 }

 void showmarks()
 {
 }

 };
 class student: public common, public education
 {
 int m;
 public:
 void getderiveddata()
 {
 common::getdata();
 cout<<"\n Enter marks=";
 cin>>m;
 }
 void showderiveddata()
 {
 common::showdata();
 cout<<m;
 }
 };
 class test:public student
 {
 };
 class employee: public common
 {
 int sal;
 public:
 void getderivedd1data()
 {
 common::getdata();
 cout<<"\n Enter salary=";
 cin>>sal;
 }
 void showderivedd1data()
 {
 common::showdata();
 cout<<sal;
 }
 };
 void main()
 {
 student s;
 s.getderiveddata();
 s.showderiveddata();
 employee e;
 e.getderivedd1data();
 e.showderivedd1data();
 getch();
 }