(A,1, ,B,R)
(B,1,1,B,R)
(B, ,1,C,R)
(C, , ,D,L)
(D,1,1,D,L)
(D, , ,A,R)
(C,1,1,E,L)
(E,1, ,F,L)
(F,1,1,F,L)
(F, ,1,G,S)