With no explanation, label each line with "location-GPE", "O", "person-scholar", "art-broadcastprogram", "art-film", "art-music", "art-other", "art-painting", "art-writtenart" or "building-airport" preceded by ":".
In
1955
,
Jonas
Salk
invented
a
polio
vaccine
which
was
given
to
more
than
seven
million
American
students
.
In:O
1955:O
,:O
Jonas:person-scholar
Salk:person-scholar
invented:O
a:O
polio:O
vaccine:O
which:O
was:O
given:O
to:O
more:O
than:O
seven:O
million:O
American:location-GPE
students:O
.:O