All French buildings begin on the \\"ground floor\\" (\\"rez-de-chaussee\\"), and then proceed to the first, second, etc.
In a sense, this is easier to remember in the U.S.
In France:
\\"First floor\\" = \\"one flight of stairs\\"
\\"Second floor\\" = \\"two flights of stairs\\"
etc.
(Whereas in the U.S. the first floor equals zero flights of stairs, and the second floor is one flight!)
So remember this simple rule:
Floor number = Flights of stairs to get there!