How many months after Armenian troops captured the city of Nakhchivan and destroyed the Republic of Aras was a cease-fire signed?
return Armenian troops captured the  city of Nakhchivan and  destroyed the Republic of  Aras ;return a cease-fire was  signed ;return month of #1 ;return month of #2 ;return the  difference of #4 and  #3
['select', 'select', 'project', 'project', 'arithmetic']