Number-guessing Game

Larry likes playing the number-guessing game.

Two players are needed in a game. Suppose they are X and Y, and X presents a number for Y to guess. Firstly, X chooses a number with four different digits, keeping it in mind, and tells Y to start guessing. Every time Y has guessed, X should give out *A*B to show Y how close to the number his answer is. Here the symbol * stands for a number, and the number before A is the number of digits in Y's answer with both correct value and position. The number before B is the number of digits in Y's answer with correct value but incorrect position.

For example, if X chooses the number 5204, and Y guesses 4902, then X should give out 1A2B, in which 1A corresponds for digit 0 with both correct value and position and 2B corresponds for digit 2 and 4 with correct value but incorrect position. Then Y will go on guessing according to 1A2B that X presents him until he gets the totally correct number 5204 (when X shows him 4A0B).

Now you are given two numbers, and what you need to do is just testing how close they are.