(;
AW[jb][lb][mb][nb][jc][kc][mc][rc][sc][ld][nd][od][pd][qd][re]
AB[la][ma][na][kb][ob][rb][sb][nc][oc][pc][qc]PL[W]
C[Endgame problem: White to gain as much as she can.
Sente is not important.
]
(;W[qb];B[qa]
(;W[oa];B[pa]
(;W[ka]
(;B[oa];W[ra]C[RIGHT Black should have sacrificed the 3 stones.
])
(;B[pb];W[oa]C[RIGHT
])
)
(;W[ra];B[pb];W[ka];B[sa];W[oa]C[RIGHT
])
(;W[sa];B[pb])
)
(;W[pa];B[pb];W[ka];B[oa]C[White could have captured three stones.
])
(;W[ra];B[pb];W[oa];B[pa];W[ka];B[sa];W[oa]C[RIGHT
])
(;W[ka];B[oa])
)
(;W[pa];B[qa]
(;W[ka];B[oa])
(;W[ra];B[sa])
)
(;W[qa];B[qb]
(;W[pa];B[ra])
(;W[ra];B[pa])
)
(;W[oa];B[pa];W[ka];B[oa]
(;W[qa];B[qb])
(;W[ra];B[qb])
(;W[qb];B[ra])
)
(;W[ra];B[qb];W[pa]
(;B[oa];W[qa]C[
];B[ka]
C[This is seki but inferior to the correct solution as black was able to rescue the marked stone.
]
TR[kb])
(;B[qa];W[oa];B[pb];W[oa]C[
];B[pa]C[This would be fatal for black.
])
)
(;W[ka];B[oa])
)