Three Seashells is a solitaire game, played on a connected undirected graph $G.$ Initially, three tokens are placed on distinct start verices $a,b,c.$ In each turn, you muse move all three tokens, by moving each token along an edge from its current vertex to an adjacent vertex. At the end of each tum, the three tokens must lie on three different vertices. Your goal is to move the tokens onto three goal vertices $x,y,z$; it does not matter which token ends up on which goal vertex

cashells puzze and the first two turns of a solution

Seashells porme algorithm to determine whether a given Three vertices $a,b,$ is solvable. Your input consists of the graph $G,$ the start or Finuse.