1   2   3   4   5   6   7
  +---+---+---+---+---+---+---+
  |                           |
 1| B                         |
  |                           |
  +   +   +   +---+   +   +   +
  |           |               |
 2|         A |               |
  |           |               |
  +   +   +---+   +   +   +   +
  |                           |
 3|                     ?     |
  |                           |
  +   +   +   +   +   +   +   +
  |                           |
 4|                         C |
  |                           |
  +---+---+---+---+---+---+---+
robot A moves north
    1   2   3   4   5   6   7
  +---+---+---+---+---+---+---+
  |                           |
 1| B       A                 |
  |                           |
  +   +   +   +---+   +   +   +
  |           |               |
 2|           |               |
  |           |               |
  +   +   +---+   +   +   +   +
  |                           |
 3|                     ?     |
  |                           |
  +   +   +   +   +   +   +   +
  |                           |
 4|                         C |
  |                           |
  +---+---+---+---+---+---+---+
robot A moves east
    1   2   3   4   5   6   7
  +---+---+---+---+---+---+---+
  |                           |
 1| B                       A |
  |                           |
  +   +   +   +---+   +   +   +
  |           |               |
 2|           |               |
  |           |               |
  +   +   +---+   +   +   +   +
  |                           |
 3|                     ?     |
  |                           |
  +   +   +   +   +   +   +   +
  |                           |
 4|                         C |
  |                           |
  +---+---+---+---+---+---+---+
robot A moves south
    1   2   3   4   5   6   7
  +---+---+---+---+---+---+---+
  |                           |
 1| B                         |
  |                           |
  +   +   +   +---+   +   +   +
  |           |               |
 2|           |               |
  |           |               |
  +   +   +---+   +   +   +   +
  |                           |
 3|                     ?   A |
  |                           |
  +   +   +   +   +   +   +   +
  |                           |
 4|                         C |
  |                           |
  +---+---+---+---+---+---+---+
robot C moves west
    1   2   3   4   5   6   7
  +---+---+---+---+---+---+---+
  |                           |
 1| B                         |
  |                           |
  +   +   +   +---+   +   +   +
  |           |               |
 2|           |               |
  |           |               |
  +   +   +---+   +   +   +   +
  |                           |
 3|                     ?   A |
  |                           |
  +   +   +   +   +   +   +   +
  |                           |
 4| C                         |
  |                           |
  +---+---+---+---+---+---+---+
robot B moves south
    1   2   3   4   5   6   7
  +---+---+---+---+---+---+---+
  |                           |
 1|                           |
  |                           |
  +   +   +   +---+   +   +   +
  |           |               |
 2|           |               |
  |           |               |
  +   +   +---+   +   +   +   +
  |                           |
 3| B                   ?   A |
  |                           |
  +   +   +   +   +   +   +   +
  |                           |
 4| C                         |
  |                           |
  +---+---+---+---+---+---+---+
robot B moves east
    1   2   3   4   5   6   7
  +---+---+---+---+---+---+---+
  |                           |
 1|                           |
  |                           |
  +   +   +   +---+   +   +   +
  |           |               |
 2|           |               |
  |           |               |
  +   +   +---+   +   +   +   +
  |                           |
 3|                     B   A |
  |                           |
  +   +   +   +   +   +   +   +
  |                           |
 4| C                         |
  |                           |
  +---+---+---+---+---+---+---+
robot B reaches the goal after 6 moves