$K\subset L$ Galois-extension with $Gal(L/K)=G, ord(G)=p^2$ then there are $p+3$ subextensions

Question

Let $K\subset L$ Galois-extension with $Gal(L/K)=G, ord(G)=p^2,p>0$ prime and $G$ is a elementary abelian p Group. Proof there are $p+3$ subextensions $K\subset E\subset L$.

Need some hints.