How to formally argue that there exists no efficient $A$ who can come up with a $e$ such that $$\begin{align}x&=PRF(e,0) \land \\ y &= PRF(e,1) \land \\ x &= H(y)\end{align}$$ where $H$ is a secure hash function and $|x|=|y|=\ell$?
Note that it's easy to argue that if $A$ just guesses randomly, the success probability for each guess is negligible (something like $\frac{1}{2^{\ell}}$). But how to argue there is no better algorithm than guessing?