Cherry and Squares

Cherry has a matrix $A$ consisting of $N$ rows and $M$ columns, filled with lowercase English letters. You are asked $Q$ queries. Each query is provided by four integers $x_{1}$, $y_{1}$, $x_{2}$, $y_{2}$ which define the rectangle, where ($x_{1}$, $y_{1}$) stands for the coordinates of the top left cell of the rectangle, while ($x_{2}$, $y_{2}$) stands for the coordinates of the bottom right c