# Write a python function to toggle bits of the number except the first and the last bit.
def set_middle_bits(n):
    n |= n >> 1
    n |= n >> 2
    n |= n >> 4
    n |= n >> 8
    n |= n >> 16
    return (n >> 1) ^ 1


def toggle_middle_bits(n):
    if n == 1:
        return 1
    return n ^ set_middle_bits(n)
