A lattice point in the xy-plane is a point both of whose coordinates are integers (not necessarily positive). How many lattice points lie on the hyperbola ${x}^{2}-{y}^{2}=17$ ?

I think the answer should be 4, because${x}^{2}-{y}^{2}=(x+y)(x-y)=17$ . 17 has 4 factors: 1,17, -1, and -17. But I don't know if these numbers actually work.

I think the answer should be 4, because