# K-permutation

Very easy

Execution time limit is 1 second

Runtime memory usage limit is 128 megabytes

Let's call a permutation of n numbers 1 ... n a k - permutation if any two adjacent elements in it differ by no more than k.

Find the number of k-permutations from the numbers 1 ... n.

## Input

Two integers n, k (1 ≤ k ≤ n ≤ 9).

## Output

Print the number of k-permutations from the numbers 1 ... n.

## Examples

Input #1

Answer #1

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