(;GM[1]FF[4]SZ[19]
GN[Black, please respond to this ko threat correctly.]
PC[http://senseis.xmp.net/?BeginnerExercise187]AP[GoWiki:2009]
DT[2009-04-22]
C[Diagram from http://senseis.xmp.net/?BeginnerExercise187

Black, please respond to this ko threat correctly.]
PL[W]

AB[al][am][bm][an][bn][en][fn][gn][hn][ao][fo][ap][ep][gp][aq][bq][cq][eq][dr]
AW[ak][bk][bl][cl][cm][dm][em][fm][cn][dn][bo][co][eo][bp][cp][dp][dq]

;W[er]C[W1]MN[1]

;
)
