[{"customer_id":151,"first_name":"Nakia","last_name":"Boyle","visited_places":[{"country":"Australia","cities":["Sydney","Melbourne"]}]},{"customer_id":152,"first_name":"3bs","last_name":"t0r","visited_places":[{"country":"Canada","cities":["Sydney"]},{"country":"Australia","cities":["Melbourne","Brisbane"]}]}]

db.collection.find({"visited_places":{"$elemMatch":{"country":"Australia","cities":"Sydney"}}},)