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 ":".
However
,
in
the
1950s
a
civilian
nuclear
research
program
was
started
,
a
byproduct
of
which
would
be
plutonium
.
However:O
,:O
in:O
the:O
1950s:O
a:O
civilian:O
nuclear:O
research:O
program:O
was:O
started:O
,:O
a:O
byproduct:O
of:O
which:O
would:O
be:O
plutonium:O
.:O