## Problem Description

CDGG has r different boxes and n different balls.He want to put the n balls into the r boxes,and it is not allow to left empty box.How many ways can CDGG put the n balls into the r boxes?

## Input

The input consists of several test cases. For each case,the only line contains two integer n and r,indicates the number of balls and the number of boxes.(0<=n,r<=10)

## Output

For each case,output a line contain a integer,indicates the answer.

## Sample Input

3 2

## Sample Output

6

## Source

FZU 2009 Summer Training Qualification -- Hero Revival 1