p1 {} {}p p 2 123412341234p p p pa A B C Dp pb Q A B C D Ep pc A B C Dp pabcp pABCABCABCBC A B Cp pABC ABCp pABBCp pABC CAB C AB ABC BCA B CAp pA BC DE Fp pABCABC:p pp p2p p3 :p pp p352 :p