a
b
k
l
u
v
5
6
15
16
c
d
m
n
w
x
7
8
17
18
e
f
o
p
y
z
9
10
19
20
g
h
q
r
1
2
11
12
21
22
i
j
s
t
3
4
13
14
23
24