Proving a language is not regular I need to prove that the following language is not regular


  $\{c^mb^na^n \mid n&gt;0,m\geq0\}$ 


But I am not sure how to do that for this particular one. I vaguely understand pumping lemma, but every example I see is in the form


  $\{a^nb^n \mid n&gt;0\}$


Or something similiar.  This does not help me with my problem, because I dont fully understand pumping lemma and am not sure how to do it for two variables that have no dependency on each other.  I know to take a length P from L, and I also need a string s>=P.
Which then becomes P=xyz, but it is this step that confuses me.
There are many ways to solve this. Here are some:


If $L = \{c^m b^n a^n : n&gt;0, m\geq 0\}$ were regular then so would $L \cap b^*a^*$ be.
The words $\{ b^n : n &gt; 0 \}$ are pairwise inequivalent modulo $L$, so $L$ is irregular according to Myhill-Nerode.
The pumping lemma works if you ignore the $c$ part.