I - Prefix MEX Equation

Suppose you have two arrays $x$ and $y$, both of length $m$. You can perform the following operation however many times you like: - Choose an index $i$ ($1 \le i \le m$), and swap $x_i$ with $y_i$. The pair of arrays $(x, y)$ is said to be *good* if it's possible to make their prefix MEX arrays equal by performing several such swaps. Note that: - The MEX of a set of integers is the smallest non-