1=>((a|b|\p{Nd}){1,2}|aaa|bbbb){1,2}
2bab
3aaca
4aaabbbb
5a0b
6aa0aaa
7b0aaa
8=>(\d{1,3}\.){3}\d{1,3}
91.2.3.4
101.22.333.44
111.2.3
121..2.3
13