How many of John Updike's books won a Pulitzer Prize?
{'directed': True, 'multigraph': False, 'graph': {}, 'nodes': [{'type': 'ANSWER_CANDIDATE_ENTITY', 'name_': 'Q3739104', 'id': 0, 'label': 'natural causes'}, {'type': 'QUESTIONS_ENTITY', 'name_': 'Q46525', 'id': 1, 'label': 'Pulitzer Prize'}, {'type': 'INTERNAL', 'name_': 'Q432919', 'id': 2, 'label': 'Maxwell Anderson'}, {'type': 'QUESTIONS_ENTITY', 'name_': 'Q105756', 'id': 3, 'label': 'John Updike'}], 'links': [{'name_': 'P1196', 'source': 2, 'target': 0, 'label': 'manner of death'}, {'name_': 'P166', 'source': 2, 'target': 1, 'label': 'award received'}, {'name_': 'P1196', 'source': 3, 'target': 0, 'label': 'manner of death'}]}