I need to write a pattern that will search for the correct isbn numbers in the file and later I will output them

You only need the pattern itself implemented through regular expressions

Here’s what I roughly got:

string pattern = @"b(?:ISBN(?:-1[03])?:?s*)?[-0-9]{1,5}[- ]?[0-9]+[- ]?[0-9]+[- ]?[0-9]+[- ]?[0-9X]b";

however, with the input data

ISBN 978-5-317-04434-3
ISBN 978-5-93286-181-3
ISBN 5-272-00341-1
ISBN 5-272-00251-1

ISBN 5-272---00251--1

ISBN 0-12-345678-9

it outputs:

ISBN 978-5-317-04434-3

ISBN 978-5-93286-181-3

ISBN 5-272-00341-1

ISBN 5-272-00251-1

272---00251

ISBN 0-12-345678-9

however, it is expected that it will be withdrawn

ISBN 978-5-317-04434-3

ISBN 978-5-93286-181-3

ISBN 5-272-00341-1

ISBN 5-272-00251-1