50 50
0 0 0 3 4 0 6 7 0 9 0 -1 0 13 0 15 16 15 0 19 0 0 22 22 24 25 26 27 24 -1 30 29 22 33 33 0 36 37 -1 36 40 41 41 -1 44 -1 45 47 47 36