Create a class Person with member data name, ID, constructor, destructor and member function display.
Create a class Student_info, which inherits class Person, in which member data for faculty number, group and faculty are added. The class contains a constructor, member functions for accessing the data, for change of ID and for displaying the data.
Add Class Student_marks, which inherits class Student_info and contains marks in 3 subjects, constructor, member function show () to display the marks and member function av() to calculate the average grade.