instruction:
In this task, you're given an open-domain question. Your task is to provide an answer to the given question. There is only one unique answer for each question. Your answer should be short, and refer to an entity, date, number, etc. Do not put your answer in the context of a sentence.
question:
Who was the 20th prime minister of canada?
answer:
Jean Chretien


question:
Who's the little girl that played in waterworld?
answer:
Tina Marie Majorino


question:
When did leningrad changed back to st petersburg?
answer:

6 September 1991