(;GM[1]FF[4]SZ[19]
GN[Why is B2 forced?]
PC[https://senseis.xmp.net/?100ChallengingGoProblemsFor100DaysOfStudy/Problem1]AP[GoWiki:2009]
DT[2024-02-28]
C[Diagram from https://senseis.xmp.net/?100ChallengingGoProblemsFor100DaysOfStudy/Problem1

Why is B2 forced?]
PL[W]

AB[ec][cd][qe][cj][pp][oq][qq][qr]
AW[pc][qo][cp][qp][eq][kq][rq]
CR[qe]
LB[od:a][qg:b][ql:c][rr:d]

;W[po]C[W1]MN[1]
;B[qi]C[B2]MN[2]
;W[op]C[W3]MN[3]
;B[nq]C[B4]MN[4]
;W[pq]C[W5]MN[5]
;B[pr]C[B6]MN[6]

;CR[qe]
LB[od:a][qg:b][ql:c][rr:d]
)
