With no explanation, label each line with "location-GPE", "O", "art-broadcastprogram", "art-film", "art-music", "art-other", "art-painting", "art-writtenart", "building-airport" or "building-hospital" preceded by ":".
In
1971
,
Mars
was
at
its
closest
to
Earth
since
1956
and
in
May
of
that
year
both
the
Soviet
Union
and
the
United
States
made
new
attempts
to
reach
the
Red
Planet
.
In:O
1971:O
,:O
Mars:location-GPE
was:O
at:O
its:O
closest:O
to:O
Earth:location-GPE
since:O
1956:O
and:O
in:O
May:O
of:O
that:O
year:O
both:O
the:O
Soviet:location-GPE
Union:location-GPE
and:O
the:O
United:location-GPE
States:location-GPE
made:O
new:O
attempts:O
to:O
reach:O
the:O
Red:O
Planet:O
.:O