Merges: 6 + 7 -> 10 (modularity 0.00) 2 + 4 -> 11 (modularity -0.07) 8 + 10 -> 12 (modularity -0.04) 3 + 11 -> 13 (modularity 0.02) 9 + 12 -> 14 (modularity 0.08) 1 + 13 -> 15 (modularity 0.16) 0 + 15 -> 16 (modularity 0.25) 5 + 14 -> 17 (modularity 0.35) 16 + 17 -> 18 (modularity 0.45)