Bridges
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Connect all the islands with a network of bridges.  Each
island shows the total number of connected bridges.
An island can have multiple bridges joining up, down, 
left or right, but bridges may not cross.

All the islands have to join together and have the 
right number of bridges.

Move the joystick while holding A to build a bridge.
Move the joystick while holding B to place a "no-bridge" 
marker.

Press A or B on an island to "lock" it.
Press A or B on an island again to "unlock it".
