MOD = 10 ** 9 + 7
fac = [1] * (10 ** 5 + 10)
for i in range(len(fac) - 1):
    fac[i + 1] = fac[i] * (i + 1) % MOD

n, k = map(int, input().split())
ans = 0
for i in range(k + 1):
    t = fac[k] * pow(fac[k - i], MOD - 2, MOD) * \
        pow(fac[i], MOD - 2, MOD) * pow(k - i, n, MOD) % MOD
    if i % 2:
        ans -= t
    else:
        ans += t
print(ans % MOD)