Matteo, I didn't take the fact that Black chooses his arrangement after
White is finished with his into account. My error in not noticing this.
In this case, if any balancing is needed, limiting White to two moves on
the first turn should be quite sufficient. I think my rule is about right
for a triple move game with a) fixed setup b) random setup or c) players
choose setup by placing one piece at a time in turns.