sub list {
  my $words=shift;
  chomp $words;
  my @words=split /\s/, $words;
  my @longs=();
  for my $i (1..$#words-1) {
    push @longs, map { join " ", @words[$_..$_+$i]} (0..$#words-$i);
  }
  push @words, @longs,$words;
  return @words;
}