The program reads strings of the form: "lastName,firstName,grade1,grade2,grade3,grade4"

The program shall add the grades, and assign a letter grade based on the following criteria: - 'A' if the sum of the grades is 90 or more, - 'B' if the sum of the grades is between 80 and 89, - 'C' if the sum of the grades is between 70 and 79, - 'D' if the sum of the grades is between 60 and 69, - 'F' if the sum of the grades is 59 or less. The output of the program shall have the form: "firstName lastName letterGrade"