How many more Navajo were killed during the expedition against the Navajo of western New Mexico compared to those who were captured?
return western New Mexico ;return the  Navajo of #1 ;return #2 that were killed during the  expedition ;return #2 that were captured during the  expedition ;return number of  #3 ;return number of  #4 ;return the  difference of #5 and  #6
['select', 'project', 'filter', 'filter', 'aggregate', 'aggregate', 'arithmetic']