#! /usr/bin/env raku

unit sub MAIN (Int $N where $N > 0, :v(:$verbose));

my $seq := gather
{
  my $current = 1;
  take 1;
  
  loop
  {
    my $new = "";
    my $add = True;
    
    for $current.comb.reverse -> $digit is copy
    {
      if $add
      {
        if $digit <= 2
	{
	   $digit++;
	   $add = False;
	}
	else { $digit = 1; }
      }
      
      $new = $digit ~ $new;
    }

    $new = "1$new" if $add; 
    $current = $new;
    
    take $current unless $current ~~ /11/;
  }
}

say ": Sequence: ", $seq[^$N].join(', ') if $verbose;
say $seq[$N-1];