4
0 0 1 1 0 1 0 1 2 1 1 3 1 -1 2 1 0 4 Hint1st step: paint (0, 0) into color 1. 000 010 000 2nd step: paint (1, 0) into color 1. 0000 0110 0000 3rd step: paint (0, 1) into color 2. 0000 0200 0110 0000 4th step: paint (1, 1) into color 3. 0000 0230 0110 0000 5th step: paint (1, -1) into color 2. 0000 0230 0110 0020 0000 6th step: paint (1, 0) into color 4. 0000 0230 0140 0020 0000