Show that for any $L_1, L_2\in Lag(E,\omega)$ there exists a symplectic basis in which $L_1=<e_1,..,e_n>$ and $L_2 =<e_1,...,e_k,f_{k+1},..,f_n>$

Question

I'm a beginner on sympletic geometry, studiyng by the Meinrenken notes, need a help in a question.

Let $(E,\omega)$ sympletic space and $L_1, L_2\in Lag(E,\omega)$ lagrangians such that $dim(L_1\cap L_2)=k$. Show that exists a symplectic basis in which $L_1=\langle e_1,..,e_n\rangle$ and $L_2 =\langle e_1,...,e_k,f_{k+1},..,f_n\rangle$.

Need some hint to start the exercises.