a
s
a
f
a
b
s
b
f
b
e
f
+
s
+
e
M
a
b
+
c
d
:
For RE
a
b
+
c
d
:
c
s
c
f
c
d
s
d
f
d
e
e
e
e
M
(
a
b
+
c
d
)*
:
a
s
a
f
a
b
s
b
f
b
e
f
+
s
+
e
M
a
b
+
c
d
:
c
s
c
f
c
d
s
d
f
d
e
e
e
e
RE
to FA:
Example
3
/3
28
/2
9
f
s
e
e
e
For a final RE
(
a
b
+
c
d
)
*
:
e