def prime_sieve(N):
    #sieve[i] : iの最小の素因数
    sieve = [0] * (N + 1)
    prime = []
    for i in range(2, N + 1):
        if sieve[i] == 0:
            sieve[i] = i
            prime.append(i)
        for p in prime:
            if p > sieve[i] or i * p > N:
                break
            sieve[i * p] = p
    return sieve


def gen_prime():
    U = 5 * 10 ** 6
    sieve = prime_sieve(U)
    for i in range(2, U):
        if i == sieve[i]:
            yield i


def main():
    M = int(input())
    prime = gen_prime()

    ans = []
    for n in reversed(range(1, 40)):
        add = pow(2, n) - 1
        while M >= add:
            M -= add
            p = next(prime)
            ans.extend([p] * n)

    print(len(ans))
    print(*ans)


main()