
111  ZOJ Monthly, October 2011  H
Give a set S, S = n, then how many ordered set group (S_{1}, S_{2}, ..., S_{k}) satisfies S_{1} ∩ S_{2} ∩ ... ∩ S_{k} = ∅. (S_{i} is a subset of S, (1 <= i <= k)) InputThe input contains multiple cases, each case have 2 integers in one line represent n and k(1 <= k <= n <= 2^{31}1), proceed to the end of the file. OutputOutput the total number mod 1000000007. Sample Input1 1 2 2 Sample Output1 9 Author: QU, Zhe 