The Sum of the k-th Powers
Description
There are well-known formulas: 
, 
, 
. Also mathematicians found similar formulas for higher degrees.
Find the value of the sum 
modulo 109 + 7 (so you should find the remainder after dividing the answer by the value 109 + 7).
The only line contains two integers n, k (1 ≤ n ≤ 109, 0 ≤ k ≤ 106).
Print the only integer a — the remainder after dividing the value of the sum by the value 109 + 7.
Input
The only line contains two integers n, k (1 ≤ n ≤ 109, 0 ≤ k ≤ 106).
Output
Print the only integer a — the remainder after dividing the value of the sum by the value 109 + 7.
4 1<br>
4 2<br>
4 3<br>
4 0<br>
10<br>
30<br>
100<br>
4<br>