(;
AB[pc][pd][oe][nd][ne][nf][ng][qg][qi][pi][oj][nj][nl][ol][pl][rj][rk][sl][sm][qm][pm][on][nn][no][oo][jp][fq][pp][qp][pq][oq][qq][qr][rr][rs][or][rp]
AW[dd][dp][cn][mo][mp][np][op][nq][lr][nr][os][ps][pr][rq][sq][sr][sp][ro][pj][qk][ql][rl][rm][om][pn][qn][po][oi][ni][nh][mg][mf][me][md][nc][od][pf]
C[Black's response to the marked White play?

Source:
    Go World #35, Spring 1984, p. 56
    Ohira Shuzo  vs.  Sugiuchi Masao
    9th Gosei, 3rd prelim. round.]
TR[pr]
(;
B[rn]
C[Shuzo makes a huge tsumego mistake.

At first glance, this throw-in looks like the
right move.  But even professionals should
double check.];
W[sn];
B[qo];
W[rn]
C[Black resigns.  The semeai is one move
short.

Shuzo said that this was the first time
in his life that he had made this kind of
tsumego mistake.

Life must be tough.]
)
    (;
    B[sk]
    C[Correct.];
    W[so];
    B[pk];
    W[ns];
    B[rn]
    C[Now the throw-in works.];
    W[sn];
    B[qo]
    )
    (;
    B[sn]
    C[Even this move, which only leads to a
sente seki, is better.];
    W[rn]
    )
)
