Air Blimp

There are $N$ cities in a row. The $i$-th city from the left has a sadness of $A_i$. In an attempt to reduce the sadness of the cities, you can send [blimps](https://en.wikipedia.org/wiki/Blimp) from the left of city $1$ that move rightwards (i.e, a blimp crosses cities $1, 2, \ldots$ in order) You are given two integers $X$ and $Y$. For each blimp sent, you can make one of the following choices