We define "$n$-$k$ special" set $X$ of positive integer numbers as follows:

• each element $x$ that belongs to set $X$ must meet the restriction $1\le x\le n$.
• the sum of elements of the set $X$ must be larger than $k$.
• no pair of elements belonging to the set can be consecutive numbers.

Write a program that reads $n$ and $k$ $(1\le n\le 100;0\le k\le 400)$ as its input and outputs the total number of "$n$-$k$ special" sets.

Sample Input

5 6

Sample Output

3

Explanation

Sets:

1. $\{1,3,5\}$
2. $\{2,5\}$
3. $\{3,5\}$

meet the given criteria. No other sets exist.