How many years between 1961 and 1989 did Real fail to win the Liga title?
return Real ;return Liga titles of #1 ;return years of #2 ;return #3 that are between 1961 and  1989 ;return number of  #4 ;return the  difference of 1989 and  1961 ;return the  difference of #6 and  #5
['select', 'project', 'project', 'filter', 'aggregate', 'select', 'arithmetic']