RL

PPA = (PPL, PPL)
PPL = (PPB, XXX)
PPB = (XXX, PPZ)
QQA = (QQL, QQL)
QQL = (QQB, XXX)
QQB = (QQC, QQC)
QQC = (QQZ, QQZ)
XXX = (XXX, XXX)
PPZ = (PPB, XXX)
QQZ = (QQB, QQB)