while (my $line = <$file>) {
    chomp $line; # remove trailing end of line character
    my @F = split /,/, $line;
    for my $i (1..3) {
        if ($F[0]+ $i == $F[1] and $F[1]+$i == $F[2]) {
            warn "row $.: $_\n";
        } else {
            print $line, "\n";
        }
    }
}