1 z
   2 \c
   3 \c2
   4 C
   5 C2
   6 x
   7 x1
   8 x1z
   9 u
  10 uz
  11 u1
  12 u1z
  13 u12
  14 u12z
  15 u123
  16 u123z
  17 x{z
  18 x{1z
  19 x{1,z
  20 x{1,2z
  21 x{10000,20000z
  22 
  23 
  24 null
  25 ]
  26 {
  27 }
  28 z
  29 c
  30 null
  31 x
  32 x
  33 x
  34 u
  35 u
  36 u
  37 u
  38 u
  39 u
  40 u
  41 u
  42 null
  43 null
  44 B
  45 null