2211. The number of n-k-special sets

We say that a set X of natural numbers is n-k-special if:

1. for every x belonging to the set X: 1 <= x <= n,

2. the sum of all integers from X is greater than k,

3. X does not contain a pair of consecutive natural numbers.

Write a program that:

• reads two natural numbers n and k,

• computes the number of n-k-special sets,

• writes the result.

输入格式

In the first line there are two natural numbers n and k separated by a single space, 1 <= n <= 100, 0 <= k <= 400.

输出格式

In the first line there should be written one non-negative integer, which equals the number of n-k-special sets for the given n and k.

样例

Input
5 6

Output
3


4 人解决，6 人已尝试。

5 份提交通过，共有 14 份提交。

7.7 EMB 奖励。