Ricky has N different balls and John has R different bags. Their teacher Ms.Samara wants them to distribute these N balls into R bags such that each bag gets at least one ball.
Can you find the number of ways of doing so ?
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

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