use Data::Dumper
my(@list_a)=(qw(a b c d e f g));
my(@list_b)=(qw(a c e g h j k));
my(%just_a,%just_b,%both);

@just_a{@list_a}=(); delete @just_a{@list_b};

@just_b{@list_b}=(); delete @just_b{@list_a};

@both{@list_a}=(); delete @both{keys %just_a};

print Data::Dumper->Dump([
      [keys %just_a],[keys %just_b],[keys %both]
  ],
  [qw/just_a just_b both/]
)