LR

11A = (11B, XXX)
11B = (XXX, 11Z)
11Z = (11B, XXX)
22A = (22B, XXX)
22B = (22C, 22C)
22C = (22Z, 22Z)
22Z = (22B, 22B)
XXX = (XXX, XXX)
33A = (33Z, XXX)
33Z = (XXX, 33A)
44A = (44B, XXX)
44B = (XXX, 44C)
44C = (44Z, XXX)
44Z = (XXX, 44C)
55A = (55B, XXX)
55B = (XXX, 55Z)
55Z = (55C, XXX)
55C = (XXX, 55Z)