Bipartite Graphs and Matchings · Challenge problem

Men $A,B,C,D$ rank women $W,X,Y,Z$ as $A\!:\!W,X,Y,Z$; $B\!:\!X,W,Z,Y$; $C\!:\!Y,W,X,Z$; $D\!:\!Z,Y,X,W$. Women rank men as $W\!:\!B,A,D,C$; $X\!:\!A,C,B,D$; $Y\!:\!D,B,A,C$; $Z\!:\!C,A,D,B$. For the matching $A\text{-}Z, B\text{-}Y, C\text{-}X, D\text{-}W$, how many blocking pairs does it have?