Problem
Write PROLOG predicate moveblock(B,X,S1,S2) to move a block from the stack S1 to the stack S2. S1 and S2 are integer numbers identifying one of the three stacks (1,2 or 3). A block can be moved only if it is at the top of a stack (otherwise it cannot be moved) and it can be only placed on top of another stack (or on the ground if the stack is empty). The predicate has to print the status of the blocks before and after the move (only if the block can be moved!).