MOD = 10**9 + 7

def main():
    import sys
    input = sys.stdin.read().split()
    N = int(input[0])
    M = int(input[1])
    
    if M == 0:
        print(0)
        return
    
    # Precompute factorials and inverse factorials up to M
    fact = [1] * (M + 1)
    for i in range(1, M + 1):
        fact[i] = fact[i-1] * i % MOD
    
    inv_fact = [1] * (M + 1)
    inv_fact[M] = pow(fact[M], MOD-2, MOD)
    for i in range(M-1, -1, -1):
        inv_fact[i] = inv_fact[i+1] * (i+1) % MOD
    
    def comb(m, k):
        if k < 0 or k > m:
            return 0
        return fact[m] * inv_fact[k] % MOD * inv_fact[m - k] % MOD
    
    ans = 0
    for k in range(1, M+1):
        c = comb(M, k)
        pow_k = pow(k, N, MOD)
        term = c * pow_k % MOD
        if (M - k) % 2 == 1:
            term = (MOD - term) % MOD
        ans = (ans + term) % MOD
    
    print(ans)

if __name__ == '__main__':
    main()