How many more points did John McAllister have than Scott Safran playing Asteroids?
return John McAllister ;return Scott Safran ;return points playing Asteroids of #1 ;return points playing Asteroids of #2 ;return sum of #3 ;return sum of #4 ;return difference of #5 and  #6
['select', 'select', 'project', 'project', 'aggregate', 'aggregate', 'arithmetic']