Labor Day is coming. Boss Niu has prepared
n identical gifts for his staff generously, and all of the gifts will be given away. It is known that in Boss Niu's company, there are
m staff in total. Due to limited gifts, each of the staff can get at least one gift, and at most
k gifts.
Now Boss Niu wonders how many different ways can he distribute his gifts. Two ways are considered different if exists one staff at least, who gets
x gifts in the first way and gets
y gifts in the second way(
x=y). Please note that all the gifts are considered same.
Since the answer may be large, you only need to output it modulo
100000007.