I'm working through some of the questions in a textbook and I'm stuck on the following pumping lemma question.
$L_1 = \Big\{w \in \{0,1\}^* \mid\text{ every prefix of }w\text{ has at least as many zeroes as ones}\Big\}$
I've worked through some very easy examples but this one has me stumped. Any tips on where to go with this?
EDIT: The goal of this question is to prove that $L_1$ is not regular