Lina the Magician claims that a common modern computer can easily perform a hundred billion operations per second! To prove it, she proposes to run the following calculations.
Let $$$V$$$ be a set of integers, initially empty. We are given the starting value of the integer $$$s$$$. Make $$$n$$$ steps described below:
How many elements will there be in $$$V$$$ after $$$n$$$ steps?
Formally: on each step, we count the number of pairs $$$(a, b)$$$ where $$$a \in V$$$, $$$b \in V$$$, $$$a \le b$$$ and $$$a + b = s$$$.
The first line contains integers $$$n$$$ and $$$s$$$ ($$$1 \le n \le 200\,000$$$; $$$0 \le s < 999\,983$$$; $$$s \ne 742\,681$$$).
Print a single integer: the size of set $$$V$$$ after $$$n$$$ steps.
4 179629
3
In the example, the values of $$$s$$$ on the four steps are $$$740\,740$$$, $$$139\,655$$$, $$$469\,353$$$, and $$$880\,395$$$.