Shortestpath

Problem descripton: given a string as following: 4,A,B,C,D,A-B,B-D,B-C,C-D the first is a number: number of nodes the for followins strings are the nodes the last four strings are linen betweens the node. your challenge is to find shourtes path from the first node to the las node with regard of connection line betweens the nodes. in this cas it shall be A-B-D.