How many fewer members of the Khatri caste was there than the Brahmin caste?
return Khatri caste  ;return members of #1 ;return Brahmin caste  ;return members of #3 ;return number of  #2 ;return number of  #4 ;return difference of #6 and  #5
['select', 'project', 'select', 'project', 'aggregate', 'aggregate', 'arithmetic']