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: "What kind of transit system is the M1 part of?" whose answer is 24/7 rapid transit system.
Each document should contain about 30 words, and these documents should contain useful information.

Query: M1 subway line
Useful Output:

Doc 1: The M1 line is a traditional heavy-duty metro line with a platform length standard of 110 m and six-car trains of 105-109 m, with a maximum capacity of 1,200-
Doc 2: The M1 metro (Rho Fiera/Bisceglie) has 38 stations departing from Sesto 1° Maggio FS and ending at Rho Fieramilano.
Doc 3: The first stop of the M1 metro route is Las Adjuntas and the last stop is Alí Primera. M1 (Alí Primera) is operational during everyday. Additional information:
Doc 4: Europe's second underground railway made its inaugural journey more than 100 years and is still used by thousands daily.
Doc 5: The M1 was revolutionary in many ways. It was the first underground railway in continental Europe powered by electricity, setting a precedent