numCities(20).
maxStations(14).

road(18,19).
road(6,18).
road(1,12).
road(11,19).
road(3,15).
road(3,6).
road(2,15).
road(10,15).
road(4,7).
road(7,9).
road(12,13).
road(10,13).
road(13,20).
road(9,12).
road(13,14).
road(11,18).
road(3,8).
road(9,14).
road(19,20).
road(3,5).
road(10,14).
road(17,20).
road(3,11).
road(6,10).
road(9,18).
road(1,10).
road(2,4).
road(4,13).
road(15,17).
road(8,19).
road(2,8).
road(5,14).
road(7,9).
road(8,20).
road(4,10).
road(11,12).
road(7,12).
road(7,18).
road(2,14).
road(10,18).
road(6,11).
road(4,18).
road(6,20).
road(4,11).
road(8,18).
road(9,15).
road(5,13).
road(1,11).
road(10,17).
road(10,16).
road(3,20).
road(1,4).
road(16,18).
road(5,6).
road(11,16).
road(13,18).
road(10,20).
road(2,9).
road(1,18).
road(6,12).
road(9,19).
road(3,9).
road(15,16).
road(11,16).
road(12,16).
road(2,12).
road(12,15).
road(2,11).
road(1,19).
road(15,18).
road(11,13).
road(2,8).
road(2,13).
road(9,14).
road(7,17).
road(16,17).