What is "werstok"

Werstok (, Verstok) is a village in the administrative district of Gmina Dubicze Cerkiewne, within Hajnówka County, Podlaskie Voivodeship, in north-eastern Poland, close to the border with Belarus. It lies approximately south-east of Dubicze Cerkiewne, south of Hajnówka, and south of the regional capital Białystok.