Morgan Trucking Company operates a special pickup and delivery service between Chicago and six other cities located in a four-state area. When Morgan receives a request for service, it dispatches a truck from Chicago to the city requesting service as soon as possible. With both fast service and minimum travel costs as objectives for Morgan, it is important that the dispatched truck take the shortest route from Chicago to the specified city. Assume that the following network (not drawn to scale) with distances given in miles represents the highway network for this problem.

A network diagram between seven parties, distributed across four columns, is shown. The left-most column contains node 1 labeled "Chicago." The second column contains nodes 2, 3, and 4. The third column contains nodes 5 and 6. The right-most column contains node 7. Arcs are shown between various locations. The following list contains the numbers placed on the graph.

• 12: 38
• 13: 33
• 14: 23
• 21: 38
• 23: 11
• 25: 15
• 31: 33
• 32: 11
• 34: 12
• 35: 13
• 36: 23
• 41: 23
• 43: 12
• 47: 18
• 52: 15
• 53: 13
• 56: 8
• 57: 23
• 63: 23
• 65: 8
• 67: 8
• 74: 18
• 75: 23
• 76: 8

Find the shortest-route distance from Chicago to node 6.