A lot of cars

There are $M$ levels for a building numbered from $1$ to $M$ from top to bottom, each level having $N$ parking spots numbered from $1$ to $N$ from left to right. Some spots might have a car while other may be empty, the information of which is given in form of two dimensional character array $C$ ($C_{i, j}$ denote parking spot at $j$-th position on $i$-th level). There is a thief who wants to u