use strict;

my %h = ();

$h{$_}=1 for (0 .. 100);

while(1) {
  print "choose a number: " . 
        join(",",sort { $a <=> $b } keys %h,"q") . 
        "\n";
  my $in = <STDIN>;
  chomp $in;
  if ($in eq "q") { last; }
  delete $h{$in};
}

print "remaining: " . 
      join(",", sort { $a <=> $b } keys %h) . 
      "\n";