Given a factoid/trivia type question, generate the topic of the question. The topic is the entity the question talks about.

Example Input: Who married the woman who was to become Queen Beatrix of the Netherlands, on 10 March 1966?
Example Output: beatrix

Example Input: Which British Prime Minister married Clementine Hozier on September 12th 1908?
Example Output: clementine churchill

Example Input: Cristina Fernandez de Kirchner became President of which South American country in December 2007?
Example Output:
president of argentina