With no explanation, label each line with "O", "art-broadcastprogram", "art-film", "art-music", "art-other", "art-painting", "art-writtenart", "building-airport", "building-hospital" or "building-hotel" preceded by ":".
During
the
last
glacial
period
,
as
well
as
in
many
earlier
ice
ages
,
virtually
the
entire
country
was
covered
with
a
thick
ice
sheet
.
During:O
the:O
last:O
glacial:O
period:O
,:O
as:O
well:O
as:O
in:O
many:O
earlier:O
ice:O
ages:O
,:O
virtually:O
the:O
entire:O
country:O
was:O
covered:O
with:O
a:O
thick:O
ice:O
sheet:O
.:O