Problem: 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

Solution (in PYTHON):

Solution:
from sys import stdin
fa = [1]
for x in xrange(1,205):
	fa.append(x*fa[x-1])
a = stdin.readline().split()
n = int(a[0])
r = int(a[1])
if n<r:
	print -1
elif n==r:
	print 1
else:
	n = n-r
	r = r-1
	n = n+r
	fir = fa[n]
	sec = fa[r] * fa[n-r]
	fir = fir/sec
	sec = 10000007
	print fir%sec