So what is that symbol. In browser my code return false with "123 " param. But not here.

Because you change the list's length and skip values. See what your code does here

Which error? Please copy and paste it here. Have you tried clicking reset just in case you modified the sample tests without noticing?

Your code worked fine for me, and please, mark your post as having spoiler content next time.

There's a space after the 3, so it is four characters, but not all characters are digits.