Consider the following language over $=\{O,B\}$ :

HONEST$=\{\begin{array}{c}w|w\end{array}$ has even length and has the form $B^n$ or $w$ has odd length and has the form $\{$:$O^n\}$

For example, BB $in$ HONEST, OOOOO $in$ HONEST, BBBB $in$ HONEST,

and $inHONEST,$ but

BBB $!in$ HONEST, BO $!in$ HONEST, and OOOO $!in$ HONEST.

Write a regular expression and regular grammar for HONEST.