How many years after the war against the Latgallian and Selonian countries started did Latgallian countries finally become the possession of German conquerors?
return the  war against the   Latgallian  and  Selonian countries  ;return Latgallian  countries  finally did become the  possession of German conquerors ;return year of #1 ;return year of #2 ;return difference of #3 and  #4
['select', 'select', 'project', 'project', 'arithmetic']