Lily, you probably already have an answer to this question so I am responding mainly to give other home buyers a heads up.
Working with an agent is the way to go if you are considering a home purchase. Ask your agent about buyer agency and how it will protect you - as a home buyer.
If you talk directly to the listing agent - you become a client of the listing broker and you lose a lot of protection in a real estate transaction.
Being represented by a selling boker - with buyer agency - costs you nothing out of pocket (in most instances - negotiable) but can save you thousands of dollars in a home purchase.