== Format of input files ==
There are two input files: student information and workstation information.  I
describe the format of both below.

Both input files allow comments.  A comment begins at any point with a hash
character ("#") and goes until the end of the line.

The student information file contains one or more lines which look like so:
Smith|John|14
As you see, there are three fields separated by a vertical pipe character.
The first field is the student's last name.  The second field is his first
name.  The third field is a comma-separated set of strings which represent the
workstation(s) at which the person usually sits.  The workstation identifiers
are given so that the program can ensure that no student is randomly selected
to sit at his usual workstations.  This third field can be left blank, but
each line must have two vertical pipes no matter what.
Lexical grammar:
	FILE = LINES
	LINES = LINE + "\n"
	LINE = (LASTNAME + "|" + FIRSTNAME + "|" + WKSTLIST) | USELESS
	WKSTLIST = WKSTMID + WKSTLAST
	WKSTMID = WKSTMID + WKSTIDENTIFIER + "," | nil
	WKSTLAST = WKSTIDENTIFIER
	WKSTIDENTIFIER = one or more printable characters | nil
	LASTNAME = one or more printable characters
	FIRSTNAME = one or more printable characters
	USELESS = COMMENT | whitespace + COMMENT | nil
	COMMENT = "#" + anything else except "\n"

The workstation information file is much simpler: it simply contains the list
of usable workstation identifiers, one number per line.

== Two sample input files ==
students.txt:
Smith|John|1	# John Smith typically uses workstation 1
Doe|Jane|2,6,C	# Jane Doe typically uses workstations 2, 6, and C
Gray|Michael|3
Perry|Angela|4
# Lozano|Jose|5	# he is on a long vacation
Mirraway|Jane|	# Jane can be assigned to any workstation

workstations.txt:
1
2
3
4
5
# 6 is broken until Tuesday
7
A
B
C