Start
  p
    'a'@(1:1-1:2)
    Nodes[Nq]
      q
        'b'@(1:2-1:3)
        Nodes[Nr]
          r
            'c'@(1:3-1:4)
            'c'@(1:4-1:5)
        'b'@(1:5-1:6)
      q
        'b'@(1:6-1:7)
        Nodes[Nr]
          r
            'c'@(1:7-1:8)
            'c'@(1:8-1:9)
          r
            'c'@(1:9-1:10)
            s
              'd'@(1:10-1:11)
            'c'@(1:11-1:12)
        'b'@(1:12-1:13)
    'a'@(1:13-1:14)
  Eof@(1:14-1:14)=''