(;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]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]TR[kb]C[This is seki but inferior to the correct solution as black was able to rescue the marked stone.
RIGHT])(;W[ka];B[qa]))(;W[ka];B[oa]))