A.AB+D*E/FA+*DC+ B.ABD*+EFAD*+/C+ C.ABDEFADC+*+/+*+ D.AB+D*EFAD*+/+C+
A.rear-front+m)%m B.rear-front+1 C.rear-front-1 D.rear-front
A.1,2,3,4,5,6 B.3,2,6,4,5,1 C.2,4,6,5,3,1 D.6,5,4,3,2,1