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 ":".
After
reconnaissance
over
the
next
two
days
the
16th
and
36th
Guards
Corps
attacked
at
1100
hours
on
April
20
but
made
little
progress
,
which
did
not
change
the
following
day
.
After:O
reconnaissance:O
over:O
the:O
next:O
two:O
days:O
the:O
16th:O
and:O
36th:O
Guards:O
Corps:O
attacked:O
at:O
1100:O
hours:O
on:O
April:O
20:O
but:O
made:O
little:O
progress:O
,:O
which:O
did:O
not:O
change:O
the:O
following:O
day:O
.:O