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

• for every x ∈ X we have 1 ≤ x ≤ n,
• the sum of all integers from X is greater than k,
• X does not contain a pair of consecutive natural numbers.

Write a program that:

• reads two natural numbers n and k from the standard input,
• computes the number of n-k-special sets,
• writes the result to the standard output.

In the first line of the standard input there are two natural numbers n and k separated by a single space, 1 ≤ n ≤ 100, 0 ≤ k ≤ 400.

출력 형식

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

예제 입력

5 6

예제 출력

3