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 ":".
A
considerable
area
of
the
city
centre
was
flooded
by
this
unprecedented
combination
of
events
.
A:O
considerable:O
area:O
of:O
the:O
city:O
centre:O
was:O
flooded:O
by:O
this:O
unprecedented:O
combination:O
of:O
events:O
.:O