This is a CRITICAL clarification for problem B, please pay attention to it. Notice that the elimination check will only happen **after the player moved a drop**. If the player takes a drop and then put it back without moving it, (i.e. length of path = 0) this won't be count as a move and no drops will be eliminated. On the other hand, once the player moved a drop out of its original place, even if the player then move it back and the puzzle looks exactly the same as it originally was, the game will begin its elimination check. Sorry for inconvenience.