(;GM[1]FF[4]CA[UTF-8]AP[CGoban:3]ST[2]
RU[Japanese]SZ[19]KM[0.00]
AW[db][dc][cd][dd][be]AB[eb][gb][ec][ed][ce][de][bf][cg]LB[bb:C][cb:D][bc:A][bd:B][ae:E]
(;B[bc]
;W[bd]
;B[ba]
;W[cb]
;B[bb]
;W[ac]
(;B[ae]
;W[ab]
(;B[aa]
;W[ad]
;B[da]C[+]
;W[af]C[in the Gokyo Shumyo version of this problem, the black stone C13 is at B13 in order to prevent this variation, and so this is the correct answer.]
;B[ca]
;W[bg]
;B[cf]
;W[bh])
(;B[da]
;W[ca]C[SEKI]))
(;B[ab]
;W[ae]C[KO]
;B[da]
;W[ca]
;B[ea]
;W[cc]
;B[ad]C[(direct ko, Black takes first)]))
(;B[cb]
;W[bb]
;B[bc]
;W[cc]
;B[bd]
;W[ca]
;B[ab]
;W[aa]C[KO (direct ko, Black takes first)]))
