H r b

H r bH r bH r bH r b
H r bH r bH r bH r bH r bH r bH r bH r b
H r bH r bH r bH r bH r bH r bH r bH r bH r bH r bH r bH r b
H r bH r bH r bH r bH r bH r bH r bH r bH r bH r bH r bH r bH r bH r bH r bH r b
H r bH r bH r bH r bH r bH r bH r bH r b