Make All Equal

You are given an array $A$ of $N$ elements and a positive integer $M$ such that $1 \leq A_i \leq N$. You can perform the following operation on $A$: - Select **at most** $M$ elements of $A$ and increase all of the selected elements by $1$. Find the **minimum** number of operations required to make all elements of $A$ equal. It can be shown that for given constraints, it is always possible to m