With no explanation, label each line with "O", "location-bodiesofwater", "location-GPE", "event-attack/battle/war/militaryconflict", "product-ship", "art-broadcastprogram", "art-film", "art-music", "art-other" or "art-painting" preceded by ":".
Siegfried
was
a
``
wolfpack
``
of
German
U-boats
that
operated
during
the
battle
of
the
Atlantic
in
World
War
II
.
Siegfried:product-ship
was:O
a:O
``:O
wolfpack:product-ship
``:O
of:O
German:location-GPE
U-boats:O
that:O
operated:O
during:O
the:O
battle:O
of:O
the:O
Atlantic:location-bodiesofwater
in:O
World:event-attack/battle/war/militaryconflict
War:event-attack/battle/war/militaryconflict
II:event-attack/battle/war/militaryconflict
.:O