Some n≥3 cities are connected with railways, so that you can travel from one city to every other, not necessarily directly. However, the railways are structured in such a way that there is only one way to get from one city to another, assuming you don't pass through the same city again. Let A be the set of these cities and railways. Show that there exists a Subset of A, let's say C, such that(1) C has at least [(n+1)/2] cities as its element.(2) No two elements of C are directly connected with railways. combinatoricsgraph theory