1   2   3   4   5   6   7
  +---+---+---+---+---+---+---+
  |                           |
 1| B                         |
  |                           |
  +   +   +   +---+   +   +   +
  |           |               |
 2|         A |               |
  |           |               |
  +   +   +---+   +   +   +   +
  |                           |
 3|                     b     |
  |                           |
  +   +   +   +   +   +   +   +
  |                           |
 4|                         C |
  |                           |
  +---+---+---+---+---+---+---+
no solutions with 4 or fewer moves