// A binary tree
digraph {
	node [shape=box]
	1 [label="A-Z"]
	2 [label="A-M"]
	3 [label="N-Z"]
	4 [label="A-F"]
	5 [label="G-M"]
	6 [label="N-S"]
	7 [label="T-Z"]
	8 [label="A-C"]
	9 [label="D-F"]
	10 [label="G-I"]
	11 [label="J-M"]
	12 [label="N-P"]
	13 [label="Q-S"]
	14 [label="T-V"]
	15 [label="W-Z"]
	16 [label=A]
	17 [label="B-C"]
	18 [label=D]
	19 [label="E-F"]
	20 [label=G]
	21 [label="H-I"]
	22 [label="J-K"]
	23 [label="L-M"]
	24 [label=N]
	25 [label="O-P"]
	26 [label=Q]
	27 [label="R-S"]
	28 [label=T]
	29 [label="U-V"]
	30 [label="W-X"]
	31 [label="Y-Z"]
	32 [label=B]
	33 [label=C]
	34 [label=E]
	35 [label=F]
	36 [label=H]
	37 [label=I]
	38 [label=J]
	39 [label=K]
	40 [label=L]
	41 [label=M]
	42 [label=O]
	43 [label=P]
	44 [label=R]
	45 [label=S]
	46 [label=U]
	47 [label=V]
	48 [label=W]
	49 [label=X]
	50 [label=Y]
	51 [label=Z]
	1 -> 2
	1 -> 3
	2 -> 4
	2 -> 5
	3 -> 6
	3 -> 7
	4 -> 8
	4 -> 9
	5 -> 10
	5 -> 11
	6 -> 12
	6 -> 13
	7 -> 14
	7 -> 15
	8 -> 16
	8 -> 17
	9 -> 18
	9 -> 19
	10 -> 20
	10 -> 21
	11 -> 22
	11 -> 23
	12 -> 24
	12 -> 25
	13 -> 26
	13 -> 27
	14 -> 28
	14 -> 29
	15 -> 30
	15 -> 31
	17 -> 32
	17 -> 33
	19 -> 34
	19 -> 35
	21 -> 36
	21 -> 37
	22 -> 38
	22 -> 39
	23 -> 40
	23 -> 41
	25 -> 42
	25 -> 43
	27 -> 44
	27 -> 45
	29 -> 46
	29 -> 47
	30 -> 48
	30 -> 49
	31 -> 50
	31 -> 51
}