Typing Speed program

Create a C++ program that logs the person’s typing speed from user input and shows it to them.  The program must include all of the following methods:
OOP format
inheritance(derived classes)
file handling classes( open(), read(), write() from #include <fstream> )
user interaction(cout/cin),
arrays and data objects (Linked Lists, Binary Trees(struct Node*).

Make the program as simple as possible (while using the above mentioned methods) and place as many explanatory comments with the code as possible.

I have uploaded an example that uses C for reference, however your code must be original and in C++.