http://www.graphviz.org/Download..php
Draw a undirect graph
1 graph g { 2 37 -- 22; 3 37 -- 83; 4 5 22 -- 19; 6 22 -- 31; 7 8 83 -- 64; 9 83 -- 87; 10 11 31 -- 24; 12 64 -- 73; 13 14 }