sub k{
  my @g;
  for( sort{ $s{$b} <=> $s{$a} } keys %s ){
    last if $s{$_} < 3;
    next unless y/a-z// > 2;
    my @f;
    push @f, (pos($t)-3) while $t =~ /$_/g;
    my $g = c n@f;
    $g > 2 && push @g, $g
  }
  c@g
}