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 ":".
He
retired
at
age
28
,
after
suffering
a
knee
injury
.
He:O
retired:O
at:O
age:O
28:O
,:O
after:O
suffering:O
a:O
knee:O
injury:O
.:O