context free

Question

Let $L = \{a^nb^nc^nd^n | n\ge1\}$. Show that $L$ can be expressed as the intersection of

two context-free languages.

Comments

can be done using intersection of 3 context free language

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can u do it ?

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L1 = {a^n b^n c^m d^k}

L2 = {a^n b^m c^m d^k}

L3 = {a^n b^k c^m d^m}

 where  n,k,m>=1

The intersection of these three languages.