my %hash = map {($_ => undef)} <>;
print sort keys %hash;

##</code><code>##

my $prev=<>;
my $count=1;
while (<>) {
   if ($prev eq $_) { $count++ }
   else {
       printf "%4d %s", $count, $prev;
       $count = 1;
       $prev = $_;
   }
}
printf "%4d %s", $count, $prev;