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:
__author__ = 'suryansh'
def factorial(n):
    f=1
    i=1
    while(i<=n):
        f=f*i
        i=i+1
    return f
line=raw_input().split(" ")
N=int(line[0])-1
R=int(line[1])-1
result=factorial(N)/(factorial(R)*factorial(N-R))
if result:
    print(result%10000007)
else:
    print("-1")