Find the number of ways of distributing N objects into R groups such that each group gets 1 or more objects.

Input:
The one and only line of input contains two numbers separated by a single space, which are N and R respectively.

Output:
The corresponding answer modulo 10000007 in a  single line and if no answer exist then print "-1".

Constraints:
1 ≤ N ≤ 100
1 ≤ R ≤ 100  

SAMPLE INPUT
4 2

SAMPLE OUTPUT
3

Explanation

Let the 2 groups be A and B respectively.
Case 1: A gets 1 object and B gets 3
Case 2: A gets 2 objects and B gets 2
Case 3: A gets 3 objects and B gets 1
from math import factorial
str=raw_input()
k,l=str.split()
k=(long)(k)
l=(long)(l)
k-=1
l-=1
x=factorial(k)
y=factorial(l)
if l>k:
	print -1
else:
	z=factorial(k-l)
	#print x,y,z
	print (x/(y*z))%10000007