Key idea. Moving a stone changes its location, not the total number of stones.

1. The original piles contain \(3+5+7=15\) stones altogether.

2. Moving one stone out of a pile removes 1 there but adds 1 to another pile. The total stays 15 after every move.

3. The proposed final piles would contain \(4+6+10=20\) stones. Since \(20\ne15\), they cannot be reached.

Remember. Check a simple total before experimenting with many moves.