A10223 | The Sum of the k-th Powers

There are well-known formulas: , , . Also mathematicians found similar formulas for higher degrees.

Find the value of the sum  modulo $10^{9}+7$ (so you should find the remainder after dividing the answer by the value $10^{9}+7$ ).

The only line contains two integers $n,k$ ( $1<=n<=10^{9},0<=k<=10^{6}$ ).

Print the only integer $a$ — the remainder after dividing the value of the sum by the value $10^{9}+7$ .