Unique Challenge Sets

You are given two non-negative integers N and K representing the total number of available challenges and the number of challenges that each participant must choose, respectively.

Your task is to compute the number of unique sets of challenges that a participant can select. Formally, you need to compute the binomial coefficient:

$$ \binom{N}{K} = \frac{N!}{K!(N-K)!} $$

Note: When K = 0 or K = N, the result is 1.

inputFormat

The input consists of a single line that contains two integers N and K separated by a space.

outputFormat

Output a single integer which is the number of unique challenge sets possible, computed as the binomial coefficient \( \binom{N}{K} \).

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