If the Series $\sum C_{n} x^{n}$ Has a Radius of Convergence of 4 And

Short Answer

If the series $\sum C_{n} x^{n}$ has a radius of convergence of 4 and $\sum D_{n} x^{n}$ has a radius of convergence of 6, what is the radius of convergence of $\sum\left(C_{n}+D_{n}\right) x^{n}$ ?