please help

Write a program that will allow a user to enter 3 grades into a gradebook and produce the average of the grades, the maximum grade entered and an overall letter grade using the following functions:

NOTE: The functions should be called from main.

1. Create a function to display a message about the program to the user

2. Create a function that determines the maximum value of the 3 grades passed to it and stores the maximum in a variable using a value-returning function.

3. Create a function that is passed the 3 grades and calculates the average and prints it

4. Create a function that is passed the average and returns the overall letter grade which is printed from main

using C++ and void functions .