"[(2N???1)+(2N???1???1)N] switches divided into two switch groups; wherein N is a natural number, each switch includes a first contact and a second contact, the first contacts of the (2N???1) switches in the first switch group are connected to ground, the second contacts of the (2N???1) switches in the first switch group are connected to the wires in (2N???1) connectors, the first contacts of the (" . . . .