Task
Time limit: 1000 ms,
Memory limit: 256 Mb

Non-negative integers n and k are given. It is necessary to output the number of combinations of n by k.
The formula for the number of combinations (you must remember that 0! = 1):
\(C^k_n=\frac{n!}{k!(n-k)!}\)

Input: integers n and k, each from a new line (each number is not more than 10, \(n >= k\))
Output: need to print one number in response

Example

¹	Input	Output
1	3 2	3
2	4 4	1