N, M = map(int, input().split())
MOD = 10**9 + 7

fac = [1] * (M + 1)
for i in range(1, M + 1):
    fac[i] = fac[i - 1] * i % MOD
rev_fac = [1] * (M + 1)
rev_fac[M] = pow(fac[M], MOD - 2, MOD)
for i in range(M - 1, 0, -1):
    rev_fac[i] = rev_fac[i + 1] * (i + 1) % MOD
comb = [1] * (M + 1)
for i in range(1, M + 1):
    comb[i] = fac[M] * rev_fac[i] * rev_fac[M - i] % MOD

if N < M:
    print(0)
else:
    res = 0
    for i in range(M):
        v = comb[i] * pow(M - i, N, MOD)
        if i % 2 == 0:
            res += v
        else:
            res -= v
    print(res % MOD)