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