$2.($Chap$.5,10$ points, $5$ points each$)$ For any PRG G : $\{0,1\}$ $\{0,1\}$ $+$l there will be many strings in $\{0,1\}$ $+$l that are impossible to get as the output of G$.$ Let S be any such set of impossible G$-$outputs, and consider the following adversary that has S hard$-$coded: $($a$)$ What is the advantage of A in distinguishing L G prg$$real from L G prg$$rand$?$ Is it negligible? $($b$)$ Does an adversary like this one automatically break every PRG$?$ Why or why not?