The hotel is counting people.

Most hotels charge by room, not by how many people live in your room. So it only costs 400 for two people to live in a room. But you have to see how breakfast is calculated. Some rooms only contain one breakfast, some contain two, and some don't!

Few hotels charge per head unless there are extra beds (that is to say, there are only two beds in a room, but for three people, extra beds will be charged)!