Problems
Matrioshkas
Matrioshkas
On the table are N matreshkas of different sizes. Smaller doll can be placed inside the larger one that, in turn, into still greater, and so on.
How many ways can be placed inside the other part of the dolls to remain exactly K matreshkas?
Input data
The input file contains integers N and K (1 ≤ K ≤ N ≤ 12).
Output data
You want to display the output file a single integer - the desired number of ways.
Examples
Input example #1
3 1
Output example #1
1