In the country of PUMACsboro, there are n distinct cities labelled 1 through n. There is a rail line going from city i to city j if and only if i<j; you can only take this rail line from city i to city j. What is the smallest possible value of n, such that if each rail line’s track is painted orange or black, you can always take the train between 2019 cities on tracks that are all the same color? (This means there are some cities c_{1}, c_{2}, \ldots, c_{2019}, such that there is a rail line going from city c_{i} to c_{i+1} for all 1 \leq i \leq 2018, and their rail lines’ tracks are either all orange or all black.)