differential equations – From SSP = {x-> 0, y-> 1} How to get SSP1 = {0,1}?

My question is this:

g = -Sqrt[1 - y^2]; h = Sqrt[1 - x^2]; Vars = {x, y};

ssp1 = Solve[{g == 0, h == 0}, Vars]

I understand this

$ { {x a -1, y a -1 }, {x a -1, y a 1 }, {x a 1, y a -1 }, {x a 1, y a 1 } } $

My question is how from this to get SSP = {{- 1, -1}, {- 1,1}, {1, -1}, {1,1}}?

I need this, to make a modification for my program. PLOT OF DOMAIN OF DIFFERENTIAL EQUATIONS.