(;
GM[1]
SZ[19]
AW[dd][cf][qh][ql][pp][jp]
AB[fc][jd][oc][qd][qj][dp]
TR[qh]
C[Problem 119. Black to play.  

White has invaded with the marked stone. How should Black respond ? ]
(;B[pi]
TE[2]
C[Correct Answer.  

Since Black has a strong position at the top. he should attack the white stone with the diagonal move of 1. Next ... ]
;W[qe]
C[White will first play the forcing moves of 2 ... ]
;B[pd];W[rd]
C[... and 4, ... ]
;B[rc];W[og]
LB[se:C][sd:B][rf:A][rd:4][qe:2]
C[... then jump to 6. White 2 and 4 gives White the option of getting eye shape with a ko by playing the sequence White A - Black B - White C. ]
;B[ni];W[mg];B[li];W[kg];B[ji];W[ig];B[hi];W[gg];B[fi]
C[Black boldly chases White up to 15, ]
;W[eg];B[hd]
LB[qn:D]
C[... then defends the top with 17. Black now aims to invade at D. This result is a great success for Black. White has obtained no territory, while Black has built a massive wall in the center. ]
;W[lc]
TR[hd]
C[After Black defends with the marked stone, invading with White 18 is unreasonable. ]
;B[nf];W[ng];B[lf];W[lg];B[jf]
LB[nf:19][lf:21]
C[Black peeps with 19, 21, and 23, ... ]
;W[jg];B[kb]
C[... then plays 25, and the territory at the top belongs to Black. <= ]
)
(;B[oj]
C[Failure.  

Jumping to Black 1 is a slack move. ]
;W[rj]
C[White can easily make sabaki by attaching underneath with 2. <= ]
)
(;B[oi]
C[Failure.  

The knight's move of Black 1 is also slack. ]
;W[pj];B[pi];W[qi];B[pk];W[rj];B[oj];W[qk]
C[White can link up her stones with the sequence to 8. <= ]
)
)