With no explanation, label each line with "location-GPE", "O", "person-politician", "art-broadcastprogram", "art-film", "art-music", "art-other", "art-painting", "art-writtenart" or "building-airport" preceded by ":".
Mithridates
,
who
had
been
rebuilding
his
forces
,
launched
an
invasion
of
Bithynia
.
Mithridates:person-politician
,:O
who:O
had:O
been:O
rebuilding:O
his:O
forces:O
,:O
launched:O
an:O
invasion:O
of:O
Bithynia:location-GPE
.:O