18
15
111000000001111
111000000011110
111000000111100
111000001111000
111000011110000
111000111100000
111001111000000
111011111000000
111111111100000
111111011100000
111110011110000
111100001110000
111000000111000
111000000111100
111000000011100
111000000001110
111000000001111
111000000000111
