question: How many of Dan Brown's books does Professor Robert Langdon appear in?
answerText: 5
questionEntity.name: Q7345
questionEntity.entityType: entity
questionEntity.label: Dan Brown
questionEntity.mention: Dan Brown's
questionEntity.name: Q210548
questionEntity.entityType: entity
questionEntity.label: Robert Langdon
questionEntity.mention: Robert Langdon
answerEntity.name: Q182502
answerEntity.label: Angels & Demons
answerEntity.name: Q81689
answerEntity.label: The Da Vinci Code
answerEntity.name: Q211006
answerEntity.label: The Lost Symbol
answerEntity.name: Q4845793
answerEntity.label: Inferno
answerEntity.name: Q30610044
answerEntity.label: Origin