rewrite < plus_n_Sm. rewrite < plus_n_Sm.rewrite < sym_plus.reflexivity.
simplify.
rewrite > nat_compare_n_m_m_n.
-simplify.elim nat_compare ? ?.simplify.reflexivity.
+simplify.elim nat_compare.simplify.reflexivity.
simplify. reflexivity.
simplify. reflexivity.
elim y.simplify.reflexivity.
simplify.rewrite > nat_compare_n_m_m_n.
-simplify.elim nat_compare ? ?.simplify.reflexivity.
+simplify.elim nat_compare.simplify.reflexivity.
simplify. reflexivity.
simplify. reflexivity.
simplify.rewrite < plus_n_Sm. rewrite < plus_n_Sm.rewrite < sym_plus.reflexivity.