graceful labelings satisfy the following properties:(i) The vertex X< sub> 0 may be attached
to one among the combinations (e, o, e),(e, e, o),(0, o, e) and (0, e, o).(ii) The path H\{X<
sub> 0} can be partitioned into subpaths p< sub> i, 1≤ i≤ k with the following properties:(a)
P< sub> i consists of at most four vertices.(b) Each vertex in P< sub> i is attached to an odd
(or even) number of branches. If each vertex in p< sub> i is attached to an odd number of …