use strict;

my %planets;
my %cuantas_veces_sale;

for my $nombre (sort keysort keys %cuantas_veces_sale) {
    print "$nombre\n";
};

sub keysort {
    return $planets{$a} <=> $planets{$b} if $planets{$a} <=> $planets{$b};
    
    my ($num_a) = $a =~ /(\d+)/;
    my ($num_b) = $b =~ /(\d+)/;
    $num_a <=> $num_b;
}