(;
GM[1]
SZ[19]
AW[cf][dk][dn][cn][bm][ho][hq][nq][ol][ql][qc][qd][rf][rg][cd][dc][hc][pb][qb][nc][fs][gs][gr][jq][kq][qk][ro][rn][sp][rq][qq][lr][lp]
AB[dp][pd][pp][dd][gc][bn][bo][co][fp][fq][fn][pn][nn][qj][pc][pe][qf][qg][cc][gd][ob][oc][fr][dr][es][qh][qo][qp][rp][oq][nr][mr][mq][lq][kp][ko]
LB[cd:1][dc:3][cc:2]
C[Problem 125. Black to play.  

This position arose later in the game in Problem 121. White attaches with 1, then crosscut with 3. How should Black continue ? ]
(;B[cb]
TE[2]
C[Correct Answer.  

The proverb advises extending when caught in a crosscut. Descending to Black 1 is the best move. ]
;W[bd];B[ec];W[de];B[ed]
C[Black and White settle the upper left with the sequence to 5. ]
;W[kc]
C[White uses her sente to stake out a position at the top, but ... ]
;B[nd]
C[... Black will block at 7. With Black's thick positions on the left and right, White is going to run for her life. <= ]
)
(;B[ed]
C[How the game continued.  

Extending to Black 1 here was also a good move, but ... ]
;W[bc];B[cb];W[be];B[bb];W[ab];B[ec];W[kc]
C[... White's shape in the upper left ended up with a bit more eye potential than in the Correct Answer. In any case, the result here was almost the same. <= ]
)
)