(related to Problem: A Railway Puzzle)
This little puzzle may be solved in as few as nine moves. Play the engines as follows: From $9$ to $10,$ from $6$ to $9,$ from $5$ to $6,$ from $2$ to $5,$ from $1$ to $2,$ from $7$ to $1,$ from $8$ to $7,$ from $9$ to $8,$ and from $10$ to 9. You will then have engines $A, B,$ and $C$ on each of the three circles and on each of the three straight lines. This is the shortest solution that is possible.
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