Bipartite Graphs and Matchings · Medium problem

Men $A,B,C$ rank women as $A: X,Y,Z$; $\;B: Y,Z,X$; $\;C: Z,X,Y$. Women rank men as $X: A,B,C$; $\;Y: B,C,A$; $\;Z: C,A,B$ (so every person's own top choice is actually free to accept them). For the matching $A\text{-}Z, B\text{-}X, C\text{-}Y$ (each person's LAST choice), how many blocking pairs does it have?