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 ":".
Barracks
blockhouses
were
used
to
house
troops
in
forts
in
Upper
Canada
.
Barracks:O
blockhouses:O
were:O
used:O
to:O
house:O
troops:O
in:O
forts:O
in:O
Upper:O
Canada:location-GPE
.:O