bezicna

if i have 3 villages:
0 100
0 200
0 400

can first and third communicate using the second so that d is 200 or d is 300?

and same question for the situation when we have some antennas, can some villages communicate by using an antenna that is in the village near them or they can use only their own antenna?

The comunication is transitive, so if i can comunicate with j and j with k, i can communicate with k without signal reaching k, as far as I remember.