F x z

F x zF x zF x zF x zF x zF x zF x zF x zF x zF x zF x zF x zF x zF x zF x zF x zF x zF x zF x zF x zF x zF x zF x zF x zF x zF x zF x zF x zF x zF x zF x zF x zF x zF x zF x zF x zF x zF x zF x zF x zF x zF x zF x zF x zF x zF x zF x zF x z