With no explanation, label each line with "location-GPE", "O", "product-airplane", "art-broadcastprogram", "art-film", "art-music", "art-other", "art-painting", "art-writtenart" or "building-airport" preceded by ":".
The
incident
is
the
largest
officially
acknowledged
loss
of
life
for
federal
troops
in
Chechnya
in
2007
and
the
worst
Russian
military
aircraft
disaster
since
August
2002
,
when
an
enormous
Mil
Mi-26
transport
helicopter
packed
with
troops
crashed
into
a
minefield
after
being
hit
by
a
missile
,
killing
20
soldiers
.
The:O
incident:O
is:O
the:O
largest:O
officially:O
acknowledged:O
loss:O
of:O
life:O
for:O
federal:O
troops:O
in:O
Chechnya:location-GPE
in:O
2007:O
and:O
the:O
worst:O
Russian:O
military:O
aircraft:O
disaster:O
since:O
August:O
2002:O
,:O
when:O
an:O
enormous:O
Mil:product-airplane
Mi-26:product-airplane
transport:product-airplane
helicopter:product-airplane
packed:O
with:O
troops:O
crashed:O
into:O
a:O
minefield:O
after:O
being:O
hit:O
by:O
a:O
missile:O
,:O
killing:O
20:O
soldiers:O
.:O