With no explanation, label each line with "O", "organization-sportsteam", "event-sportsevent", "art-broadcastprogram", "art-film", "art-music", "art-other", "art-painting", "art-writtenart" or "building-airport" preceded by ":".
The
Yankees
were
the
defending
World
Series
champions
,
while
Boston
had
not
appeared
in
the
ALCS
since
1990
.
The:O
Yankees:organization-sportsteam
were:O
the:O
defending:O
World:event-sportsevent
Series:event-sportsevent
champions:O
,:O
while:O
Boston:organization-sportsteam
had:O
not:O
appeared:O
in:O
the:O
ALCS:event-sportsevent
since:O
1990:O
.:O