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 ":".
There
are
two
tumuli
at
Marathon
,
Greece
.
There:O
are:O
two:O
tumuli:O
at:O
Marathon:location-GPE
,:O
Greece:location-GPE
.:O