Show the following menu on the screen and take the user's choice
and perform the job of user's choice. 
Your program should be repeated until number 5 for quitting is chosen.

Which of the following would you like to do?
1.  Find the sum of 20 numbers.
2.  Find the average of 20 numbers.
3.  Find the largest of 20 numbers.
4.  Display the 20 numbers in ascending order.
5.  Quit.

Enter your selection: (1 to 5)

You must break your idea into at least three functions:

Please store 20 numbers in an array.