(;
GM[1]
SZ[19]
AW[dd][jp][jn][jl][cp][cn][dq][eq]
AB[pd][pj][pp][lp][ep][fp][fq][fm]
LB[dd:2][pd:1][pj:11][pp:3][lp:13][jp:12][jn:14][jl:16][cp:4][eq:6]
LB[dq:8][cn:10][fm:15][ep:5][fp:9][fq:7]
C[Problem 17. Black to play.  

This problem is a bit different from Problem 13. After 167, Black's four stones on the left seem to be in trouble. How can Black relieve the pressure on these stones and go on the attack ? ]
(;B[dm]
TE[2]
C[Correct Answer.  

Black should first play the forcing moves of 1 ... ]
;W[cm];B[dl]
C[... and 3, strengthening his stones on the left, ... ]
;W[ck];B[jj]
C[... then cap with 5. It is now the three white stones in the middle of the lower side that are under attack, caught between the sanren-sei formation on the right and Black's strengthened position on the left. <= ]
)
(;B[jd]
C[Failure.  

If Black neglects to strengthen his stones on the left and plays a big point at 1 instead, ... ]
;W[en]
C[... White will force with 2 ... ]
;B[fn];W[go]
C[... and 4, ... ]
;B[fo];W[fk]
C[... then cap with 6. Black's stones are now in trouble. <= ]
)
)