### A good answer might be:

`'a' - ('a' - 'A') == 'A'`, or, `'a' - 32 == 'A'`. Subtracting 32 from a lower case character results in the corresponding upper case character (in ASCII).

# Complete Program Design

Here is the complete design of the program. Glance over it to get the general idea. Its individual routines are explained in the following pages. This design uses more subroutines than usual because its purpose is to show subroutine linkage.

A subroutine starts with a pill-shaped box that shows the name of the subroutine. A box with double vertical lines for its sides (like `doLines` in `main`) designates a subroutine call. The program starts execution with `main`.

### QUESTION 12:

At the maximum, how many levels deep is subroutine nesting in this program?