(;AB[ns]AB[ms]AB[mr]AB[mq]AB[nq]AB[oq]AB[pp]AB[qp]AB[ro]AB[sn]AB[qn]AW[ps]AW[or]AW[nr]AW[pq]AW[rq]AW[qq]AW[rp]AW[sp]AW[so]C[How to response black 1 ?]LB[ns:1]AP[goproblems]
(;W[qr];B[os]
(;W[pr];B[rs];W[sr];B[rr]C[Seki. Black and White can't approach. You can do better.])
(;W[rs];B[pr];W[or])
(;W[sr]
(;B[rs]
(;W[pr])
(;W[qs];B[pr]C[You can save these two stones.])
(;W[rr];B[pr]C[You can save these two stones.]))
(;B[pr];W[or])))
(;W[pr];B[rr]
(;W[sr];B[rs]
(;W[qr];B[os]C[Seki. You can do better.])
(;W[qs];B[os]C[Seki. You can do better.]))
(;W[rs];B[sr];W[qr];B[os]C[Seki. You can do better.]))
(;W[os];B[qs];W[pr]
(;B[sr]
(;W[rs];B[rr];W[qr]C[Seki. Black and White can't approach. You can do better.])
(;W[rr];B[rs]C[Seki. You can do better.]))
(;B[rr]
(;W[sr]
(;B[rs]C[Seki. Black and White can't approach. You can do better.])
(;B[ss]C[Black can also choose ko.]))
(;W[qr];B[sq])))
(;W[qs];B[os]
(;W[pr];B[rr];W[sr];B[rs]C[Seki. You can do better.])
(;W[sr];B[pr];W[qr]C[White is safe but you can save the two stones.];B[or]))
(;W[rr]
(;B[os];W[pr]C[White is safe!RIGHT])
(;B[rs];W[sr];B[os];W[pr]C[RIGHT]))
(;W[rs];B[os];W[pr]C[RIGHT])
(;W[sr];B[rs]
(;W[rr];B[os];W[pr]C[RIGHT])
(;W[pr];B[rr]
(;W[qr];B[os]C[Seki. You can do better.])
(;W[qs];B[os]C[Seki. You can do better.]))
(;W[qr];B[os]
(;W[pr];B[rr]C[Seki. Black and White can't approach. You can do better.])
(;W[qs];B[pr]C[You can save these two stones.])
(;W[rr];B[pr]C[You can save these two stones.]))))