Design and implement an application that allows the user to find the shortest path between two cities. One input to the program should be a file representing a weighted graph, as described in the case study. The vertices are labeled with the names of cities and the weight on an edge is the number of miles between two cities. The other inputs to the program come from the keyboard, and are the names of the city of departure and the city of arrival. The program should display as output the length of the shortest route between these two cities.