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.