(;
AB[fo][go][ho][cp][dp][ep][ip][bq][iq][br][ir][is]
AW[gp][cq][dq][eq][hq][cr][gr][bs][cs][hs]
C[Black plays.

But is the official solution wrong?!];
B[hr]
(;
W[gs];B[fs]
(;
W[fr]
C[The "official" solution gives this as the best defense.];
B[es];W[fp];B[gq]
C[After Black's throw-in, White only has 1 eye.]
)
    (;
    W[gq]
    C[But this unmentioned defense seems to only give Black a ko.]
    (;
    B[er];W[es]
    C[This throw-in is the key.];
    B[ds];W[fr];B[fp]
    C[And Black only has a ko that White takes 1st.]
    )
        (;
        B[fr]
        C[Fails.];
        W[fq];B[er];W[es];B[ds];W[dr]
        C[And White lives unconditionally.]
        )
        (;
        B[es]
        C[Fails];
        W[er];B[ds];W[fp]
        )
    )
)
    (;
    W[es]
    C[Also seems to lead to a ko.]
    (;
    B[fr];W[fq];B[gs];W[fs]
    )
        (;
        B[gs];W[fs]
        )
    )
)

