A cable with 12 parallel wires was layed between two cities A and
B, but they forgot to mark the ends of the wires.
Now a worker has to establish the correspondence between
wire ends at A and at B. To do the job she applies the following
procedure. She can connect somehow the ends in one city,
say in A, then go to B and use a simple electrical measuting tool
to find out for any pair of ends in B whether the corresponding
connected at A or not.
What is the minimal number of trips between A and B to complete
Also solve for arrbitrary number of wires in the cable.