Too Far For Comfort (Easy Version)

*This is the easy version of TOOFAR, and is worth $40$ points.* An array $A$ of length $M$ is said to be *prefix-balanced* under the following conditions: - Let $S_A$ denote the set of all elements that appear in $A$. - For each $x \in S_A$, and index $i$ ($1 \leq i \leq M$), let $f_i(x)$ denote the number of times $x$ appears among $[A_1, A_2, \ldots, A_i]$. That is, $f_i(x)$ denotes the frequ