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: "how many cities in india have metro railway?" whose answer is ten.
Each document should contain about 30 words, and these documents should contain useful information.

Query: number of cities with metro railway in india
Useful Output:

Doc 1: New metro rail (subway) systems are under construction and bringing about vast changes in 20+ Indian cities at a breathtaking pace.
Doc 2: India has 1,000 km of metro network across 17 cities, and is adding another 1,000 km to it. This is where and how the country is adding metro
Doc 3: How Many Metro Cities In India? Currently, India officially recognizes 8 metro cities, also called metropolitan cities or Tier-1 cities.
Doc 4: Stretching over 1,000 kilometers across 11 states and 23 cities, the network serves millions of daily passengers, making India home to the third
Doc 5: By 2024, India is expected to have over 1,100 kilometres of operational metro lines, making it one of the largest metro networks in the world.