x * y = kxykkntnniii=1,2,...,natyaaat-aaj=1,2,...,sj=1,2,3...,st-akaibia+bit-aiiit-a-biiit-a-biiibiat+aat+aiiajjj=1,2,...,njbiiikk≠ibijijijjtijbiijjtjiijjijiiijjijj=1,2,...,st+at+akk=1,2,...,nkit