∀ {V : Type u_1} {G : SimpleGraph V} {M : G.Subgraph} [inst : Fintype V] [inst_1 : DecidableEq V]
  [inst_2 : DecidableRel G.Adj] (c : G.ConnectedComponent), M.IsPerfectMatching → Even (Fintype.card ↑c.supp)