How to say if this grammar is LL(1)?


I need some help with understanding if a grammar is $ LL(1)$ or not.

$ $ \begin{align} S \rightarrow AB\ A \rightarrow a \mid \varepsilon \ B \rightarrow bCd\ C \rightarrow c \mid \varepsilon \end{align} $ $

I have computed the first and follow sets and I’ve tried to use $ LL(1)$ definition, but I don’t know how to answer it.

Thanks in advance.