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 ":".
This
bombing
occurred
only
two
days
after
a
school
in
Northern
Yemen
was
hit
in
a
Saudi
airstrike
.
This:O
bombing:O
occurred:O
only:O
two:O
days:O
after:O
a:O
school:O
in:O
Northern:O
Yemen:location-GPE
was:O
hit:O
in:O
a:O
Saudi:location-GPE
airstrike:O
.:O