CF330A Cakeminator

You are given a rectangular cake, represented as an $ r×c $ grid. Each cell either has an evil strawberry, or is empty. For example, a $ 3×4 $ cake may look as follows: The cakeminator is going to eat the cake! Each time he eats, he chooses a row or a column that does not contain any evil strawberries and contains at least one cake cell that has not been eaten before, and eats all the cake cells there. He may decide to eat any number of times. Please output the maximum number of cake cells that the cakeminator can eat.

The first line contains two integers $ r $ and $ c $ ( $ 2

Output the maximum number of cake cells that the cakeminator can eat.

For the first example, one possible way to eat the maximum number of cake cells is as follows (perform 3 eats).