(;AB[ar]AB[br]AB[bs]AB[cr]AW[cs]AW[fs]AW[fr]AW[fq]AW[eq]AW[dq]AW[cq]AW[aq]AW[bq]AP[goproblems]
(;B[dr];W[ds]
(;B[es]
(;W[er];B[ds]C[Well done:-) The black's stones is unconditionally alive.RIGHT])
(;W[ds]
(;B[er]C[Well done:-) The black's stones is unconditionally alive.RIGHT])
(;B[cs];W[er]C[You took wrong:-< The marked point isn't an eye:-...]TR[ds])))
(;B[er];W[es]C[You took wrong:-< Black dead:-...]))
(;B[ds];W[dr]TR[cs]C[You took wrong:-< The marked point isn't an eye:-...])
(;B[es]C[Black can't make eyes:-< White must play in D2 or E2:-...])
(;B[er]C[Black can't make eyes:-< White must play in D1 or D2 or E1:-...]))