I need a very simple program to output the following form the screenshot included. I'm having a hard time accepting more then one grade so any help would be greatly appreciated. Thank you!

Enter a grade: 71 Enter a grade: 85.2 Enter a grade: -2 Error. Grade must be between 0 and 100; or -1 to finish Enter a grade: -12.23 Error. Grade must be between 0 and 100; or -1 to finish Enter a grade: 99.6 Enter a grade: 73 Enter a grade: 101 Error. Grade must be between 0 and 100; or -1 to finish Enter a grade: -1 You entered 4 valid grades You entered 3 invalid grades Highest grade: 99.6 CA) Lowest grade: 71 (C) Average: 82.2 (B-) Here are the 4 valid grades: 71 CC) 85.2 (B) 99.6 (A,) 73 CC) Here are the 3 invalid grades: 12.23 101