Permutaion

As we known, there are N! permutations of {1,2,...N}. Now you are requested to find how many permutations satisfying that, the difference of every two adjacent numbers is not more than K. Because the answer may be quite large, you only need to output the answer module (%) 1,000,000,007.

You can assume 2 <= N <= 50 and 0 <= K <= 4.

There are several lines of the input. Each line indicates one test case, and contains two numbers N and K.

Output one line for each test case, indicating the answer module 1,000,000,007.

4 2

12

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