use strict;
use Data::Dumper;

my @text = <DATA>;
my @courselist;
my $LastCourseNumber;

for (@text) {
    my ( $Institution, $CourseNumber, $Professor, $Enrollment ) = split /\|/;

    last unless ( $CourseNumber && $Institution);

    if ($CourseNumber ne $LastCourseNumber) {
        push @courselist, [ $Institution, $CourseNumber,
                             $Professor, $Enrollment];
        $LastCourseNumber = $CourseNumber; 
    }
}
print Dumper( \@courselist );

@courselist =  sort { $a->[0] cmp $b->[0] || $a->[1] cmp $b->[1] } @courselist;

print Dumper( \@courselist );

__DATA__
UM|CS 34|Somebody|3
AC|PHIL 13|Another Person|8
UM|BIO 567|Someone Else|20