"""

包除原理？
m色以下 - mC1*(N-1) + mC2…
かな

"""

def modfac(n, MOD):
 
    f = 1
    factorials = [1]
    for m in range(1, n + 1):
        f *= m
        f %= MOD
        factorials.append(f)
    inv = pow(f, MOD - 2, MOD)
    invs = [1] * (n + 1)
    invs[n] = inv
    for m in range(n, 1, -1):
        inv *= m
        inv %= MOD
        invs[m - 1] = inv
    return factorials, invs


def modnCr(n,r,mod,fac,inv): #上で求めたfacとinvsを引数に入れるべし(上の関数で与えたnが計算できる最大のnになる)

    return fac[n] * inv[n-r] * inv[r] % mod

N,M = map(int,input().split())

ans = 0
mod = 10**9+7
fac,inv = modfac(M+10,mod)

for i in range(1,M+1):

    now = pow(i,N,mod) * modnCr(M,i,mod,fac,inv)
    
    if i % 2 == M % 2:
        ans += now
    else:
        ans -= now

    ans %= mod

print (ans)