Question: The input is a list of league game scores (and there are no ties). If all teams have at least one win and a loss, we can generally "prove," by a silly transitivity argument, that any team is better than any other. For instance, in the six-team league where everyone plays three games, suppose that we have the following results: A beat B and C; B beat C and F; C beat D; D beat E; E beat A; and F beat D and E. Then we can prove that A is better than F because A beat B who in turn beat F. Similarly, we can prove that F is better than A because F beat E and E beat A. Given a list of game scores and two teams X and Y, either find a proof (if one exists) that X is better than Y or indicate that no proof of this form can be found.