Imagine you have been recently placed in a very good company ;D and as celebration you decide to distribute chocolates to kids in your society, you being humble and rash give at least one chocolate to each kid. You tell me the total number of ways in which you can distribute R chocolates to N kids. As total number of ways can go very large so output total number ways modulo 10000007. If not possible to distribute print -1.

E.g

R = 2, N = 1

Output : 1

R = 4, N = 2

Output : 3

Okay..It's nice and you are correct.. :) though can be easily solved using dp too .. can try if you want to...