initialize the tree given in the diagram
v [ 1 ] . append ( 2 ) NEW_LINE v [ 2 ] . append ( 1 ) NEW_LINE v [ 1 ] . append ( 3 ) NEW_LINE v [ 3 ] . append ( 1 ) NEW_LINE v [ 1 ] . append ( 4 ) NEW_LINE v [ 4 ] . append ( 1 ) NEW_LINE v [ 2 ] . append ( 5 ) NEW_LINE v [ 5 ] . append ( 2 ) NEW_LINE v [ 2 ] . append ( 6 ) NEW_LINE v [ 6 ] . append ( 2 ) NEW_LINE v [ 3 ] . append ( 7 ) NEW_LINE v [ 7 ] . append ( 3 ) NEW_LINE v [ 7 ] . append ( 10 ) NEW_LINE v [ 10 ] . append ( 7 ) NEW_LINE v [ 7 ] . append ( 11 ) NEW_LINE v [ 11 ] . append ( 7 ) NEW_LINE v [ 4 ] . append ( 8 ) NEW_LINE v [ 8 ] . append ( 4 ) NEW_LINE v [ 4 ] . append ( 9 ) NEW_LINE v [ 9 ] . append ( 4 ) NEW_LINE