(\z.(\s.s z) (\n.\c.\d.n c (c d))) (\a.\b.b) -> (\s.s (\a.\b.b)) (\n.\c.\d.n c (c d)) -> (\n.\c.\d.n c (c d)) (\a.\b.b) -> \c.\d.(\a.\b.b) c (c d) -> \c.\d.(\b.b) (c d) -> \c.\d.c d