1,2,1.0 2,3,1.0 3,4,1.0 1,5,1.0 4,5,1.0 5,6,1.0 6,7,1.0 4,8,1.0 7,8,1.0 7,9,1.0 9,10,1.0 8,11,1.0 10,11,1.0 10,12,1.0 3,13,1.0 11,13,1.0 12,14,1.0 13,14,1.0 2,15,1.0 14,15,1.0 1,16,1.0 15,17,1.0 16,17,1.0 6,18,1.0 16,18,1.0 9,19,1.0 18,19,1.0 12,20,1.0 17,20,1.0 19,20,1.0