With no explanation, label each line with "location-GPE", "O", "location-bodiesofwater", "organization-other", "art-broadcastprogram", "art-film", "art-music", "art-other", "art-painting" or "art-writtenart" preceded by ":".
During
the
month
it
fought
to
retain
the
Sandomierz
bridgehead
on
the
Vistula
,
repulsing
strong
German
counterattacks
in
the
northern
sector
of
the
bridgehead
.
During:O
the:O
month:O
it:O
fought:O
to:O
retain:O
the:O
Sandomierz:location-GPE
bridgehead:location-GPE
on:O
the:O
Vistula:location-bodiesofwater
,:O
repulsing:O
strong:O
German:organization-other
counterattacks:O
in:O
the:O
northern:O
sector:O
of:O
the:O
bridgehead:location-GPE
.:O