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:
import fileinput as f
import math
def computeValue(n,r):
	n = n-1
	r = r-1
	if n>0 and r>0 and n >= r:
		print (math.factorial(n)/(math.factorial(n-r) * math.factorial(r))) % 10000007
	else:
		print -1

vals=iter(f.input())
for line in vals:
	nr = line.split(' ')
	n = int(nr[0])
	r = int(nr[1])
	computeValue(n,r)