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 ":".
These
prisoners
helped
to
maintain
rice
fields
while
local
farmers
were
serving
in
the
military
.
These:O
prisoners:O
helped:O
to:O
maintain:O
rice:O
fields:O
while:O
local:O
farmers:O
were:O
serving:O
in:O
the:O
military:O
.:O