Given a configuration of pebbles on the vertices of a graph , a pebbling move consists of taking two pebbles off a vertex and putting one of them back on a vertex adjacent to . A graph is called if for each vertex there is a sequence of pebbling moves that would place at least one pebble on . The of a graph , is the smallest integer such that is pebbleable for every configuration of pebbles on . A graph is said to be class if the pebbling number of is equal to the number of vertices in . We prove that , a class of diameter three graphs, are class .