package Person;

sub fullname {
  my $self = shift;
  if (@_) {
    $self->{fullname} = shift;
  }
  return $self->{fullname};
}

sub initials {
  my $self = shift;
  if (@_) {
    $self->fullname(join ', ', $self->surname, shift);
  }
  (split $self->fullname, ', ', 2)[1];
}

sub surname {
  my $self = shift;
  if (@_) {
    $self->fullname(join ', ', shift, $self->initials);
  }
  (split $self->fullname, ', ', 2)[0];
}