public void readOption(){
    	
    	String choice = null;
    	boolean validChoice = false;

        do {
            displayPartMenu();
            try {
                choice = sc.nextLine().trim().toUpperCase();
                System.out.println();
                
                if(choice.equals("M")){
                	validChoice = true;
                	processBackToMainMenu();
                } else { 
                    try{
                        int input = Integer.parseInt(choice);
                        if (input >= 1 && input <= 5){
                            validChoice = true;
                            displayPartClassMenu(input);
                        }// end if
                        System.out.println("Invalid Input!!!");
                    }catch (NumberFormatException e){
                        System.out.println("Invalid Input!!!");
                    } 

                }

            } catch (InputMismatchException e) {
                // display error message
                System.out.println("Please enter a valid option!");
                sc.nextLine();
            }

        } while (!validChoice);

    }