import math

mod = 1000000007

def qpow(a, b):
    if b == 0:
        return 1
    x = qpow(a, b // 2)
    x = (x * x) % mod
    if b % 2:
        return x * a % mod
    return x

# T = int(input())
T = 1

for i in range(T):
    n, k = [int(i) for i in input().split()]
    tmp = (n - 1) * qpow(n, mod - 2) % mod
    tmp = qpow(tmp, k)
    ans = ((1 - tmp + mod) % mod) * n % mod;
    print(ans * qpow(n, k) % mod)