class nCb(object):
    def __init__(self, max_n, mod = 10**9 + 7):
        self.max_n = max_n
        self.mod = mod
        self.fac = self._init_factorials()
        self.inv = self._init_inv()
        
    def _init_factorials(self):
        N = self.max_n
        mod = self.mod
        f = 1
        fac = [1] * (N + 1)
        for i in range(1, N + 1):
            f *= i
            f %= mod
            fac[i] = f
        return fac

    def _init_inv(self):
        N = self.max_n
        mod = self.mod
        ret = pow(self.fac[N], mod - 2, mod)
        inv = [1] * (N + 1)
        inv[N] = ret
        for i in range(N-1, 0, -1):
            ret *= i + 1
            ret %= mod
            inv[i] = ret
        return inv

    def get(self, n, b):
        return (self.fac[n] * self.inv[b] * self.inv[n-b]) % self.mod


def solve(N, M):
    if N < M:
        return 0
    mod = 10**9 + 7
    ncb = nCb(M, M, mod)
    ans = 0
    sig = 1
    for i in range(M, 0, -1):
        ans += sig * ncb.get(M, i) * pow(i, N, mod)
        ans %= mod
        sig *= -1
    return ans

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