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 ":".
In
April–May
1941
,
Greece
was
overrun
by
German
forces
,
and
the
country
was
occupied
by
the
Germans
,
the
Italians
and
the
Bulgarians
.
In:O
April–May:O
1941:O
,:O
Greece:O
was:O
overrun:O
by:O
German:O
forces:O
,:O
and:O
the:O
country:O
was:O
occupied:O
by:O
the:O
Germans:O
,:O
the:O
Italians:O
and:O
the:O
Bulgarians:O
.:O