BYLT BM 1788 is located about 90 metres south of the trifinium (which is almost visible in the end of the vista in the left part of this photo), but here we found the same stone as at LTPLRU. Maybe it was put here instead since the trifinium was wet? 

To left Polish border marker, to right Byelorussian border marker - and in the middle a trifinium marker (?).