Payroll Requirements Specification

Write a program that prompts the user to enter a three letter code
for the day of the week, followed by the number of hours
worked that day, then computes and displays the total amount
earned.  This version is simply interactive, and does
not read or write files.

Simplifying assumptions:
        Fixed hourly rate is built into the program.
        No over-time computations are performed.
        No tax deductions are computed.
        Input is from the keyboard, output is to the display.

Clarifying assumptions:
        The user should not have to type entries for every day of the
                week, just days worked.
        Some easy-to-remember three-letter code will signify end of input.
        Only legal values will be accepted, illegal entries will be
                gracefully ignored.