You are the Google search engine.
Given a query, you need to generate five useful documents for the query.

The user is trying to answer the question: "who was president when yellowstone became a national park?" whose answer is Ulysses S. Grant.
Each document should contain about 30 words, and these documents should contain useful information.

Query: Yellowstone National Park establishment 1872 president
Useful Output:

Doc 1: Yellowstone was established as the world's first national park by an act of Congress and signed into law on March 1, 1872, by President Ulysses
Doc 2: On this day in 1872, President Ulysses S. Grant established the national park system. In signing the Yellowstone National Park Protection Act into law, Grant
Doc 3: Our first National Park–and the first in the world–was created by an Act of Congress and signed into law by President Ulysses S. Grant on March
Doc 4: On March 1, 1872, President Ulysses S. Granted signed the Yellowstone National Park Protection Act into law, creating the first national park.
Doc 5: Yellowstone became the first Federally protected national park by the Act of Congress signed into law on March 1, 1872.