(;
GM[1]
SZ[19]
AW[dd][pq][mq][pl][oh][qc][pd][qb][oc][oe][ne]
AB[cp][eq][no][qo][nd][ng][of][pf][qe][qd][rc]
C[Problem 154. Black to play.  

A sharp encounter has taken place in the upper right. Black's stones are out in the center and he would like to play a big extension on the left. Should Black so this immediately or should he make another move on the right ? ]
(;B[qh]
TE[2]
C[Correct Answer.  

Black 1 is the most urgent point. This move makes Black's stones in the upper right absolutely safe and it also takes away space for White to make her own stones safe. ]
(;W[nl]
C[If White jumps to 2, ... ]
;B[op]
C[... Black forces with 3, ... ]
;W[oq];B[lo]
C[... then jumps to 5. White is still under attack. <= ]
)
(;W[qi]
C[If White 2 here, ... ]
;B[ri]
C[... Black will play 3. <= ]
))
(;B[qq]
C[Failure.  

If Black makes a base for his stones in the lower right with 1, ... ]
;W[qr]
C[... White will exchange 2 ... ]
;B[rq]
C[... for 3, ... ]
;W[qh]
C[... then secure her stones on the right side with 4. The black stones above are still insecure and the game now favours White. <= ]
)
)