Line 18, you are declaring a variable outside of main.
Ya, I see what might be the error. In order to print something out of a structure you have to use the member operator like with classes for each piece of data in the structure. so that would need to be... hmm. Not sure how you would write that with an array of structures. It would either be cities[sub].cityName or cities.cityName[sub]. I think it's the first since that makes more sense.