Consider the language L $=\{$d$^($p$)$ c$^(3$n$)$ b$^(2$n$)$ a$^($m$)|$ p $>$ m$,$ and m$,$ n greater than or equal to $1\}.$m$,$n$,$p are integers.$($a$)$ What is the shortest string in L if m is a multiple of $4?($b$)$ Write a context$-$free grammar to generate L$.$