RULES: After your first move your opponent cannot chose the best move. After your second move your opponent will play perfectly. What is the best result you can get?
(if there are X good replies to your first move the opponent will chose the second best of them, not the worst!).
After the first move, A marker represents the place where the best move would have been, NOT the spot you must play :-)
(;AB[pb]AB[pc]AB[qd]AB[rc]AB[re]AW[rf]AW[qf]AW[qe]AW[pe]AW[pd]AW[od]AW[oc]AW[nc]C[White to play and get a good result. Do not forget to read the rules!]AW[nb]AW[rg]AP[goproblems]
(;B[rd]C[Explanationary variation (the computer will not chose this path during solving)];W[rb];B[sb];W[qb];B[qc];W[ra];B[sd];W[pa]C[The ko goes for example something like this.])
(;B[sd]C[Black can make a ko, but white could do better. If black connected at S16 I think it is ko too, but the variations are quite complicated.CHOICE]LB[ra:A]))