(;AP[goproblems]AW[sp]AW[sq]AW[sr]AW[rs]AW[qs]AW[ns]AW[nr]AW[nq]AB[mr]AB[mq]AB[np]AB[oq]AB[or]AB[os]AB[pp]AB[qo]AB[ro]AB[so]AW[qq]TR[qq]TR[sp]TR[sq]TR[sr]TR[rs]TR[qs]C[Do your best.](;B[qr](;W[pr](;B[pq](;W[rp](;B[ps](;W[rr](;B[qp]C[Well done, ko is the best result for black.RIGHT])(;B[pr];W[qp]))(;W[qp];B[rr]))(;B[qp];W[rr];B[ps];W[qr])(;B[rr];W[rq](;B[qr];W[ps])(;B[ps];W[qr])))(;W[ps];B[rq](;W[rr];B[rp]C[RIGHT])(;W[rp];B[qp]C[RIGHT])))(;B[ps];W[pq](;B[ms];W[rq])(;B[op];W[rq])(;B[rq];W[op]))(;B[rq];W[rp](;B[pq];W[rr])(;B[ps];W[rr])(;B[qp];W[rr]))(;B[rp];W[rq])(;B[rr];W[rq]))(;W[rr](;B[pr](;W[rp](;B[qp]C[RIGHT])(;B[pq];W[qp])(;B[ps];W[qp]))(;W[qp];B[rp]C[RIGHT]))(;B[pq];W[rp](;B[qp];W[pr])(;B[pr];W[qp])(;B[ps];W[qp]))(;B[qp];W[pr](;B[ps];W[rp])(;B[pq];W[rp])(;B[rp];W[pq]))(;B[rp];W[pr](;B[pq];W[ps](;B[rq]C[RIGHT])(;B[qp];W[rq]))(;B[rq];W[pq];B[ps];W[op])(;B[ps];W[pq](;B[rq];W[op])(;B[op];W[rq]))(;B[qp];W[pq]))))(;B[rq];W[rp](;B[qp];W[qr])(;B[qr];W[pr](;B[pq];W[rr])(;B[ps];W[rr])(;B[qp];W[rr]))(;B[pr];W[qr]))(;B[pr];W[qr])(;B[rp];W[rq])(;B[rr]C[Now, white is alive unconditionary.])(;B[qp];W[qr](;B[rq];W[rp])(;B[rp];W[rq]))(;B[pq];W[qr](;B[rq];W[rp])(;B[rp];W[rq]))(;B[ps];W[qr](;B[rp];W[rq])(;B[rq];W[rp])))