2. Write a C program using switch statement that read the letter grades as an input and count the number of each different letter grade students earned on an exam. The letter grades can be uppercase (A, B, C, D, F) or lowercase (a,b,c,d,f). Your program should display the message "Invalid Grade Entered" when user enters the out of range grade Your program should also determine how many students pass the exam and fail the exam. Pass if the letter grade is above or equal to C. Fail if the letter grade is below C. 4 4