Cheap Modification

You are given an array $A$of $n$ elements. You can apply the following operation to each array element any number of times (including zero): Choose a valid index $i$ $(1\leq i\leq n)$ and increase the value of $A_i$ by 1, i.e., do $A_i = A_i + 1$. An operation costs **exactly** $1$ unit. You have to find out the minimum cost required to make the array $A$ strictly increasing. **Note:** Test fi