How many more nights stay were counted in Linz in 2013 than in 2004?
return Linz ;return nights stay counted in   #1 ;return #2 in   2013 ;return #2 in   2004 ;return number of  #3 ;return number of  #4 ;return difference of #5 and  #6
['select', 'project', 'filter', 'filter', 'aggregate', 'aggregate', 'arithmetic']