With no explanation, label each line with "O", "organization-other", "art-broadcastprogram", "art-film", "art-music", "art-other", "art-painting", "art-writtenart", "building-airport" or "building-hospital" preceded by ":".
It
is
best
known
as
burial
grounds
of
people
executed
by
the
KGB
in
1944–1947
.
It:O
is:O
best:O
known:O
as:O
burial:O
grounds:O
of:O
people:O
executed:O
by:O
the:O
KGB:organization-other
in:O
1944–1947:O
.:O