...
            $people = 1 if ($filename eq 'people.pdf');
            $animal = 1 if ($filename eq 'animal.pdf');
            $msi    = 1 if ($filename eq 'setup.msi');
        }
    }
    print "People not found\n"   unless defined $people;
    print "animal not found\n"   unless defined $animal;
    print "MSI file not found\n" unless defined $msi;
...