i forget how long, a bit over a week... and i discovered that skipping across train sleepers was easier than normal walking, and conveniently they had turned off most of the train services, until i got to Kurshumlija, which is close to the "border" with kosovo
and then i persuaded a conductor to give me a free ticket to travel to the border with Bulgaria, i forget the name of the stop
my observations about the difference between country people and city people was heavily influenced by that walk