MOD = 10 ** 9 + 7

n, m = map(int, input().split())

ans = 0
comb = 1
if m & 1:
    pm = -1
else:
    pm = 1
for i in range(m + 1):
    ans += pm * comb * pow(i, n, MOD) % MOD
    ans %= MOD
    pm *= -1
    comb *= m - i
    comb *= pow(i + 1, MOD - 2, MOD)
    comb %= MOD
print(ans)