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
IN = raw_input()
I = IN.split(' ')
N = int(I[0])
R = int(I[1])
W = 1
r = 1
if R > N :
	W = -1
	print(W)
else :
	for i in xrange(0,R-1) :
		W = (W * (N-1-i))/(i+1)
	print(W%10000007)