MOD = 10**9 + 7
list_size = 100001

f_list = [1] * list_size
f_r_list = [1] * list_size

for i in range(list_size - 1):
	f_list[i + 1] = int((f_list[i] * (i + 2)) % MOD)

f_r_list[-1] = pow(f_list[-1], MOD - 2, MOD)

for i in range(2, list_size + 1):
	f_r_list[-i] = int((f_r_list[-i + 1] * (list_size + 2 - i)) % MOD)

def comb(n, r):
	if n < r:
		return 0
	elif n == 0 or r == 0 or n == r:
		return 1
	else:
		return (((f_list[n - 1] * f_r_list[n - r - 1]) % MOD) * f_r_list[r - 1]) % MOD 

n, m = map(int, input().split())
ans = 0
for i in range(m, 0, -1):
	if (m%2) == (i%2):
		ans += pow(i, n, MOD) * comb(m, i)
		ans %= MOD
	else:
		ans -= pow(i, n, MOD) * comb(m, i)
		ans %= MOD
print(ans)