(0,19)
(1,19)
(1,18)
(1,17)
(1,16)
(1,15)
(1,14)
(1,13)
(1,12)
(2,12)
(2,11)
(3,11)
(3,10)
(4,10)
(4,9)
(4,8)
(3,8)
(2,8)
(2,7)
(1,7)
(1,6)
(1,5)
(2,5)
(2,4)
(3,4)
(4,4)
(4,5)
(4,6)
(5,6)
(6,6)
(6,7)
(7,7)
(7,8)
(8,8)
(8,9)
(9,9)
(9,10)
(9,11)
(10,11)