  1                        1
  1 1       1              1 1       1
  11        1 1       1    11        1 1
       1    11        1 1       1    11
       1 1       1    11        1 1
  1    11        1 1       1    11
  1 1       1    11        1 1       1
  11        1 1       1    11        1 1
       1    11        1 1       1    11
       1 1       1    11        1 1
  1    11        1 1       1    11
  1 1       1    11        1 1       1
  11        1 1       1    11        1 1
       1    11        1 1       1    11
       1 1       1    11        1 1
  1    11        1 1       1    11
  1 1       1    11        1 1       1
  11        1 1       1    11        1 1
       1    11        1 1       1    11
       1 1       1    11        1 1
  1    11        1 1       1    11
  1 1       1    11        1 1       1
  11        1 1       1    11        1 1
       1    11        1 1       1    11
       1 1       1    11        1 1
       11        1 1            11
                 11
