How many less tons of crude oil than Angola does Iran supply China?
return Angola ;return Iran ;return tons of crude oil of  #1 ;return tons of crude oil of  #2 ;return #3 that is supply to China ;return #4 that is supply to China ;return the  difference of #6 and  #5
['select', 'select', 'project', 'project', 'filter', 'filter', 'arithmetic']