mod = 10 ** 9 + 7
p, K = map(int, input().split())

zero = 1
other = 0  # 1, 2, ... P-1それぞれの状態数（ぜんぶいっしょ）
for _ in range(K):
    n0 = 0
    n1 = 0

    # mult 0
    n0 += zero + (p - 1) * other
    # mult 1,2,..p-1
    n0 += zero * (p - 1)
    n1 += other * (p - 1)

    # add
    n0 += zero + (p - 1) * other
    n1 += zero + (p - 1) * other

    zero = n0 % mod
    other = n1 % mod

print(zero)