20
18
000000111111100000
000011111111111000
000111111111111100
001111111111111110
011111100000111111
011110000000011111
011110000000001100
111100000000000000
111100000000000000
111100000011111111
111100000011111111
111100000011111111
111100000011111111
011110000000001111
011111000000001111
011111100000111111
001111111111111111
000111111111111110
000011111111111000
000000111111100000
