With no explanation, label each line with "location-GPE", "O", "location-road/railway/highway/transit", "location-mountain", "art-broadcastprogram", "art-film", "art-music", "art-other", "art-painting" or "art-writtenart" preceded by ":".
They
followed
the
Great
North
Trail
,
which
dipped
down
into
Montana
along
the
east
slope
of
the
Rocky
Mountains
.
They:O
followed:O
the:O
Great:location-road/railway/highway/transit
North:location-road/railway/highway/transit
Trail:location-road/railway/highway/transit
,:O
which:O
dipped:O
down:O
into:O
Montana:location-GPE
along:O
the:O
east:O
slope:O
of:O
the:O
Rocky:location-mountain
Mountains:location-mountain
.:O