Simple parking

create a number assigner that gives you the smallest number available then you plug in your number into a keypad and it is available again in the selection and can be drawn again i need the list to be from 1-200 or bigger
EX:
click a button a screen displays number one
click again displays number 2
click again displays number 3
you type number 2 into a key pad (no number 2 is available again)
click button again it displays number 2 (since its available because you already typed it in in the key pad)
click button again displays number 4 (since 1,2,3 are not available)
type number 1 into key pad (available again for drawing)
click button displays number 1
etc