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:
inp = raw_input()
inp = inp.split()

a = int(inp[0])
b = int(inp[1])

from math import factorial

a = a - b + b - 1
b = b - 1
c = a - b

if a < 0 or b < 0 or a < b:
    print "-1"
    quit()

a = factorial(a)
b = factorial(b)
c = factorial(c)

ans = a/b;
ans = ans/c;

ans = ans % (10000007)

print ans