The train routes go from 1-2, 2-3, 3-4, 4-5, ,and so on, but there is also one that goes from 25-1. If you notice, there when we get to 4-5, there are 4 train routes which means that if there are 25 towns, then there are 24 train routes, but since 25 and 1 are connected then there are 25 routes. Hope this helps!
