Confusing Concatenations

Chef initially had two non-empty arrays $A$ and $B$, where both arrays contain **distinct** elements. Moreover, there is no common element in the arrays $A$ and $B$. Chef forms another array $C$ from the arrays $A$ and $B$ using the following process : - Let $X$ denote the leftmost element of array $A$ and $Y$ denote the leftmost element of array $B$. - If $Y$ is smaller than $X$, delete $Y$ from