my $data_in="ISBN 90-70002-34-5";
   $data_in=~ s/^ISBN//;
   $data_in=~ s/ /-/g;
   $data_in=~ s/-//g;
my @isbn=split('', $data_in);
my $count=scalar @isbn;
unless (($count eq 10) && (!($count=~ m/[a-z]/i))){
   warn "not enough digits in ISBN: $count instead of 10\n";
}