o
r
d
e
r
o
f
g
r
o
u
p
,
n
1
8
0
U
p
t
o
i
s
o
m
o
r
p
h
i
s
m
,
t
h
e
f
i
n
i
t
e
A
b
e
l
i
a
n
g
r
o
u
p
s
o
f
o
r
d
e
r
1
8
0
=
2
2
2
3
1
5
a
r
e
4
×
9
×
5
≅
1
8
0
4
×
3
×
3
×
5
≅
6
0
×
3
2
×
2
×
9
×
5
≅
9
0
×
2
2
×
2
×
3
×
3
×
5
≅
3
0
×
6