Q9: Bitcoin secret key is nothing but a random number s. Suppose Bob has 10 Bitcoins, which worth quite some money, and he would like to have special protection for his wallet (in particular, the secret key). Suppose Bob has a phone, has a laptop and a usb stick, and he would like to be sure at least two of these three devices appear together, he can reconstruct the secret key, give a concrete construction for such kind of sharing scheme