I'm currently learning about one-way functions. I have a book with the following exercise (Sadly there is no solution in the book...)
Let $g\colon \{0,1\}^n \to \{0,1\}^n$ be a one way function. Prove that $f\colon \{0,1\}^{2n} \to \{0,1\}^n$ with $f(v,w) := g(v)⊕w$ is NOT a one way function.
I don't really get how I can solve this exercise... because if $w$ is, for example, $0^n$, it would be a simple reduction to show that it is in fact a one-way function, right?
How can I get an advantage $>\mathit{negligible}(n)$ ?