With no explanation, label each line with "location-GPE", "O", "art-broadcastprogram", "art-film", "art-music", "art-other", "art-painting", "art-writtenart", "building-airport" or "building-hospital" preceded by ":".
It
served
mainly
in
Baltic
territories
and
north
Russia
until
1944
.
It:O
served:O
mainly:O
in:O
Baltic:location-GPE
territories:O
and:O
north:O
Russia:location-GPE
until:O
1944:O
.:O