Probably okay for your tutorial...but country areas change from time to time due to territorial disputes being resolved, or due to older erroneous info being changed.
Cities can also change country. Pristina used to be in Serbia but is now in Kosovo (although this is not universally acknowledged). Bratislava used to be in Czechoslovakia but is now in Slovakia.
While just pedantic in this case, it demonstrates how hard it can be to create a strong data model.
