Limits Continuity And Differentiability

If \(f(x-y)=f(x) \circ g(y)-f(y) \circ g(x)\) And \(g(x-y) =g(x) \circ g(y)+f(x) \circ f(y)\) for all \(x, y \in \mathrm{R}\). If right-hand derivative at \(x=0\) exists for \(f(x)\), find the derivative of \(g(x)\) at \(x=0\)