100 miles will get you from Sumy to Kursk and Kharkov to Belgorod, and beyond, in either case. So about half of both respective oblasts, which, as an absolute,

100 miles will get you from Sumy to Kursk and Kharkov to Belgorod, and beyond, in either case. So about half of both respective oblasts, which, as an absolute, is a significant part of Russia.