There are four books in the school library: A, B, C and D. It is stipulated that each student can borrow at most two books (different books). At least ask how many people borrow the same kind of books. At least 8 people borrow books of the same type.

The reason is that the school library has four books, A, B, C and D, and it is stipulated that each student can borrow at most two books, namely 10 books, AA, AB, AC, AD, BB, BC, BD, CC, CD and D. So at least eight people borrowed the same book.