# 1061 - Fat Cat's cousin II

Time limit : 1 sMemory limit : 32 mb
Submitted : 666Accepted : 298

### Problem Description

Fat cat's son is 10 years old now(a small cat? a small mouse? who knows!), and he is doted upon by Fat cat's father-in-law. Oh,do you remember his wife, Mr fat cat is a mordon man and his wife is not a cat but a mouse, a very lovely mouse. Today, fat cat went to see his father-in-law with his family. Grandpa was very happy of course, and as a mathematician he ask his grandson a question: There are n elephants and you seperate them in k groups, how many ways there are will you seperate them? for example there are 4 elephants and you must seperate them in three groups, we name the 4 different elephants 1 2 3 4 and you can seperatet them in the following ways:



{ 1 2 } { 3 } { 4 }            or           { 1 3 } { 2 } { 4 }

{ 1 4 } { 2 } { 3 }            or           { 2 3 } { 1 } { 4 }

{ 2 4 } { 1 } { 3 }            or           { 3 4 } { 1 } { 2 }

there are six way to seperate them



then grandpa ask a lot of questions just the same except n and k are different and grandson answer them all correctly, do you know the answer to the questions?

### Input

Input The input will be pairs of integers, one pair per line, and they are all less than 21, the input will end by the end of file.

### Output

Output: For each pair of integers, print the number of ways to seperate elephants

### Sample Input


4 3
2 2


### Sample Output


6
1



PAT: The order of groups should not be considered.