In this task, you're given passages that contain mentions of the quantity of a particular object and are supposed to find out the answer for a given question. Craft one correct answer to the question given in input. Make sure your correct answer is consistent with the context, and properly gives the exact number relating to the query.
 In your answer, use as few words as possible from the given context. To be less repetitive, please vary your language for each question.

Example input: Sentence: The New York metropolitan area is home to a self-identifying gay and bisexual community estimated at 568,903 individuals, the largest in the United States and one of the world's largest. Same-sex marriages in New York were legalized on June 24, 2011 and were authorized to take place beginning 30 days thereafter. 
Question: How many people identify as gay or bisexual in NYC?
Example output: 568,903
Example explanation: There are total 568903 individuals who identify as gay or bisexual.
Q: Sentence: Montana contains thousands of named rivers and creeks, 450 miles (720 km) of which are known for "blue-ribbon" trout fishing. Montana's water resources provide for recreation, hydropower, crop and forage irrigation, mining, and water for human consumption. Montana is one of few geographic areas in the world whose rivers form parts of three major watersheds (i.e. where two continental divides intersect). Its rivers feed the Pacific Ocean, the Gulf of Mexico, and Hudson Bay. The watersheds divide at Triple Divide Peak in Glacier National Park. 
Question: How many miles of rivers are known for high class trout?
A:
450