Blood on the Number Line

Given $N \in \mathbb{N}$ , your task is to check whether $N$ is a vampire number or not. Let $N$ have $2k$ digits. Then, $N$ can be represented as $N = n_{2k} n_{2k - 1} ... n_1$, where $n_{i}$ represents the $i$-th digit of $N$, counting from $1$. $N$ is a vampire number if and only if there exist two natural numbers, $A$ and $B$, each with $k$ digits such that: $A=a_k a_{k−1} ... a_1$ $B=b_