Fox Ciel safely return castle wrong security system castle sensor attach castle cover herCiel point 11 castle want point nn position room by step Ciel point xy x1y rightward xy1 upwardIn castle c2 sensor set point aibj integer j 0ic0jcEach sensor count value decrease count value time Ciel move initially count value sensor t every time Ciel move point xy count value sensor point uv decrease uxvy when count value sensor strictly 0 sensor catch Ciel suspicious individualDetermine Ciel 11 nn catch sensor possible output step Assume Ciel point censor point