How many years after the Bolsheviks closed the Novodevichy Convent did it become a history & art museum?
return the  Bolsheviks closed the Novodevichy Convent ;return the  Novodevichy Convent did become a history & art museum ;return year of #1 ;return year of #2 ;return difference of #4 and  #3
['select', 'select', 'project', 'project', 'arithmetic']