You are tasked to write a calculator for the average score of a class. First, your program will ask the user to input $4$ grades one by one, which are expected to be values $0-100.$ Then the simple average $($mean$)$ will be calculated and printed to the screen. Bonus points if you write code to validate the grades are entered correctly. If a bad grade, say $-5,$ is entered, the program should print a message letting the user know there was a bad input and not proceed with calculating an average.

$(1)$ Write this program using a for loop. $(5$ points$)$

$(2)$ Write this program using a while loop. $(5$ points$)$