sub check_field {
    open my $fh, "<", shift or die "Bleah!\n$!";
    <$fh>;    # Skip the unwanted line.
    my @fields = split /;/, <$fh>;
    close $fh;
    die "Ick!\n" unless @fields == 4;
    return( ($fields[2] =~ /^\d+$/) ? 1 : 0 );
}