18 18
111110000000000000
111110000000000000
111110000000000000
111111000000000000
111111111110000000
000001111110000000
000001111110000000
000001111110000000
000000111110000000
000000011111000000
000000001111100000
000000001111100000
000000001111100000
000000001111100000
000000001111100000
000000000000000000
000000000000000000
000000000000000000