use common::sense;
use less 'CPU';

$\ = "\n";
<>; my @covers = <>; chomp @covers;
$_ -- foreach(@covers);
my @vertices = map
  +{ covers => $covers[$_], deg => 0, idx => $_ },
  (0..$#covers);
$vertices[$_]->{deg} ++ foreach(@covers);
my @zeroes = grep !$_->{deg}, @vertices;
my @all = @vertices;
while(my $uncovered = shift @zeroes // shift @all) {
  next if $uncovered->{used};
  my $covered = $vertices[$uncovered->{covers}];
  next if $covered->{used};
  print $covered->{idx} + 1;
  $uncovered->{used} = $covered->{used} = 1;
  my $next = $vertices[$covered->{covers}];
  push @zeroes, $next unless -- $next->{deg};
}