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e
m
G
i
v
e
n
a
n
e
xt
e
nde
d
n
e
t
w
o
r
k
=
(
,
,
,
)
,
a
s
o
ur
c
e
po
i
nt
s
a
n
d
a
s
i
nk
po
i
nt
t
.
T
h
e
t
a
s
k
r
e
qu
i
r
e
d
by
t
h
e
p
r
o
b
l
e
m
i
s
f
i
n
di
ng
t
h
e
f
l
ow
w
h
i
c
h
h
a
s
a
m
a
xi
m
u
m
v
a
l
ue
.
T
h
e
f
l
ow
v
a
l
ue
i
s
l
i
m
i
t
e
d
b
y
t
h
e
t
o
t
a
l
a
m
o
u
n
t
of
t
h
e
c
i
r
c
ul
a
t
i
o
n
po
s
s
i
b
i
l
i
t
y
o
n
t
h
e
r
o
a
ds
s
t
a
r
t
i
n
g
f
r
o
m
s
o
ur
c
e
po
i
n
t
s
.
A
s
a
r
e
s
ul
t
o
f
t
h
i
s
,
t
h
e
r
e
c
o
ul
d
b
e
a
c
o
n
f
i
r
m
a
t
i
o
n
o
n
t
h
e
f
o
l
l
ow
i
n
g
t
h
e
o
r
e
m
.
3.
2
.
Th
e
o
r
e
m
1
G
i
v
e
n
a
n
e
xt
e
n
de
d
n
e
t
w
o
r
k
=
(
,
,
,
)
,
a
s
o
ur
c
e
po
i
nt
s
a
nd
a
s
i
n
k
po
i
nt
t
,
t
h
e
n
e
x
i
s
t
i
s
t
h
e
m
a
x
i
m
a
l
f
l
ow
[1].
4.
TH
E
A
LG
O
R
I
TH
M
F
I
N
D
I
N
G
M
A
X
I
M
A
L
F
L
O
WS
4.
1
.
S
o
u
r
c
e
to
w
ar
d
s
i
n
k
al
go
r
i
th
m
In
p
ut
:
G
i
v
e
n
a
n
e
xt
e
n
de
d
n
e
t
w
o
r
k
=
(
,
,
,
)
,
a
s
o
ur
c
e
po
i
nt
s
a
nd
a
s
i
nk
po
i
n
t
t
.
T
h
e
po
i
n
t
s
i
n
g
ra
p
h
G
a
r
e
a
rr
a
nge
d
i
n
a
c
e
rt
a
i
n
o
r
de
r
[
3].
O
ut
put
:
M
a
xi
m
a
l
f
l
o
w
=
{
(
,
)
|
(
,
)
}
.
(1)
S
t
a
r
t
:
T
h
e
de
pa
rt
u
r
e
f
l
o
w
:
(
,
)
≔
0
,
∀
(
,
)
∈
.
P
o
i
n
t
s
f
r
o
m
t
h
e
s
o
ur
c
e
po
i
nt
s
w
i
l
l
g
ra
du
a
l
l
y
b
e
l
a
b
e
l
l
e
d
L
1
f
o
r
t
h
e
f
i
r
s
t
t
i
m
e
i
n
c
l
ud
i
n
g
5
c
o
m
po
n
e
n
t
s
:
F
o
r
m
f
o
r
w
a
r
d
l
a
b
e
l
1
(
)
=
[
,
1
(
)
,
1
(
)
,
1
(
)
,
1
(
)
]
a
n
d
c
a
n
b
e
l
a
b
e
l
l
e
d
(
)
f
o
r
t
h
e
s
e
c
o
n
d
t
i
m
e
2
(
)
=
[
,
2
(
)
,
2
(
)
,
2
(
)
,
2
(
)
]
.
P
ut
l
a
b
e
l
i
n
g
(
)
f
o
r
s
o
ur
c
e
po
i
n
t
L
1
(
s
)
=
[
,
,
,
,
1
]
T
h
e
s
e
t
S
c
o
m
pri
s
e
s
t
h
e
po
i
n
t
s
w
h
i
c
h
ha
v
e
a
l
r
e
a
dy
be
e
n
l
a
b
e
l
l
e
d
(
)
b
ut
a
r
e
n
o
t
us
e
d
t
o
l
a
b
e
l
(
)
,
S’
i
s
t
h
e
po
i
n
t
s
e
t
l
a
b
e
l
l
e
d
(
)
b
a
s
e
d
o
n
t
h
e
po
i
nt
s
o
f
t
h
e
s
e
t
S
.
B
e
gi
n
≔
{
}
,
′
≔
∅
(2)
F
o
r
w
a
r
d
l
a
b
e
l
ge
n
e
r
a
t
e
:
(2.
1)
C
h
o
o
s
e
f
o
r
w
a
r
d
l
a
b
e
l
po
i
n
t
:
∅
:
Ch
o
o
s
e
t
h
e
po
i
nt
o
f
a
m
i
n
i
m
u
m
v
a
l
ue
.
R
e
m
o
ve
t
h
e
u
f
r
o
m
t
h
e
s
e
t
S
,
:
=
\
{
}
.
A
s
s
um
i
n
g
t
ha
t
t
h
e
f
o
r
w
a
rd
l
a
b
e
l
of
u
i
s
[
,
(
)
,
(
)
,
(
)
,
(
)
]
,
=
1
2
.
A
i
s
t
h
e
s
e
t
o
f
t
h
e
po
i
nt
s
w
hi
c
h
a
r
e
n
o
t
f
o
r
w
a
r
d
l
a
b
e
l
t
i
m
e
a
nd
a
dj
a
c
e
nt
t
o
t
h
e
f
o
r
w
a
r
d
l
a
b
e
l
po
i
n
t
u
.
S
t
e
p
(2.
2).
Evaluation Warning : The document was created with Spire.PDF for Python.
IS
S
N
:
2088
-
8708
Int
J
E
l
e
c
&
Co
m
p
E
n
g
,
V
o
l
.
10
,
N
o
.
2
,
A
p
ri
l
2020
:
1632
-
1640
1634
=
∅
’
∅
:
≔
’
,
’
:
=
∅
.
R
e
t
urn
t
o
s
t
e
p
(2.
1
).
=
∅
’
=
∅
:
T
h
e
f
l
o
w
F
i
s
t
h
e
m
a
xi
m
u
m
.
E
nd.
(2.
2
.
)
F
o
r
w
a
r
d
l
a
b
e
l
t
h
e
po
i
n
t
s
w
h
i
c
h
a
r
e
n
o
t
f
o
r
w
a
r
d
l
a
b
e
l
a
n
d
a
r
e
a
dj
a
c
e
nt
t
o
t
h
e
f
o
r
w
a
r
d
l
a
b
e
l
po
i
n
t
s
Ca
s
e
=
∅
:
R
e
t
u
rn
t
o
S
t
e
p
(2
.
1)
.
Ca
s
e
∅
:
C
h
o
o
s
e
o
f
a
m
i
ni
m
um
v
a
l
ue
.
R
e
m
o
ve
t
h
e
v
f
r
o
m
t
h
e
s
e
t
,
∶
=
\
{
}
.
A
s
s
i
gn
f
o
r
w
a
r
d
l
a
b
e
l
e
d
po
i
n
t
v
:
If
1
)
(
),
,
(
)
,
(
,
)
,
(
u
b
i
t
v
u
c
v
u
f
E
v
u
i
E
put
f
o
r
w
a
r
d
l
a
b
e
l
po
i
n
t
v
:
(
)
∶
=
;
(
)
:
=
{
(
)
,
(
,
)
(
,
)
}
,
(
)
=
0
,
(
)
:
=
{
(
)
,
(
,
)
(
,
)
,
(
)
}
,
(
)
>
0
;
(
)
∶
=
(
)
E
v
i
v
i
f
)
,
(
,
;
(
)
:
=
1
,
(
)
>
0
,
(
)
:
=
0
,
(
)
=
0
.
If
,
)
,
(
E
u
v
(
,
)
>
0
,
put
f
o
r
w
a
r
d
l
a
b
e
l
po
i
nt
v
:
(
)
∶
=
;
(
)
:
=
{
(
)
,
(
,
)
}
,
(
)
∶
=
(
)
E
v
i
v
i
f
)
,
(
,
;
(
)
:
=
1
.
If
v
i
s
n
o
t
f
o
r
w
a
r
d
l
a
b
e
l
,
t
h
e
n
r
e
t
u
rn
t
o
S
t
e
p
(
2.
2
)
.
If
v
i
s
f
o
r
w
a
r
d
l
a
b
e
l
a
n
d
v
i
s
b
a
c
kw
a
r
d
l
a
b
e
l
,
t
h
e
n
m
a
ki
ng
a
dj
us
t
m
e
n
t
s
i
n
i
n
c
r
e
a
s
e
o
f
t
h
e
f
l
ow
.
S
t
e
p
(2.
3)
.
If
v
i
s
f
o
r
w
a
r
d
l
a
b
e
l
a
nd
v
i
s
n
o
t
b
a
c
kw
a
r
d
l
a
b
e
l
,
t
h
e
n
a
d
d
v
t
o
S’
,
’
∶
=
’
{
}
,
a
n
d
r
e
t
u
rn
t
o
S
t
e
p
(2.
2
).
(3)
M
a
ki
n
g
a
dj
us
t
m
e
n
t
s
i
n
i
n
c
r
e
a
s
e
o
f
t
h
e
f
l
o
w
:
S
uppo
s
e
s
i
s
f
o
r
w
a
r
d
l
a
b
e
l
[
,
(
)
,
(
)
,
(
)
,
(
)
]
:
(3.
1)
A
dj
us
t
m
e
n
t
m
a
de
f
r
o
m
v
b
a
c
k
t
o
s
a
c
c
o
r
di
n
g
t
o
f
o
r
w
a
rd
l
a
b
e
l
(3.
1
.
1)
S
t
a
rt
∶
=
,
∶
=
1
(
)
,
∶
=
1
(
)
.
(3.
1
.
2
.
)
M
a
ki
ng
a
dj
us
t
m
e
n
t
s
(
i
)
C
a
s
e
(
,
)
t
h
e
r
o
a
d
s
e
c
t
i
o
n
w
h
o
s
e
di
r
e
c
t
i
o
n
ru
n
s
f
r
o
m
x
t
o
y
:
put
(
,
)
∶
=
(
,
)
+
.
.
(
ii
)
Ca
s
e
(
,
)
t
h
e
r
o
a
d
s
e
c
t
i
o
n
w
h
o
s
e
di
r
e
c
t
i
o
n
ru
n
s
f
r
o
m
y
t
o
x
:
put
(
,
)
∶
=
(
,
)
.
.
(
iii
)
C
a
s
e
(
,
)
n
o
n
-
d
i
r
e
c
t
i
o
n
r
o
a
ds
:
If
(
,
)
0
(
,
)
=
0
,
t
h
e
n
put
f
(
x
,
y
)
:
=
f
(
x
,
y
)
+
.
If
(
,
)
>
0
,
t
h
e
n
put
(
,
)
∶
=
(
,
)
.
(3.
1
.
3)
M
o
v
i
n
g
(i
)
C
a
s
e
=
.
.
S
t
e
p
(3.
2).
(i
i
)
,
∶
=
:
=
,
i
s
t
h
e
s
e
c
o
n
d
c
o
m
po
n
e
nt
o
f
t
h
e
f
o
r
w
a
r
d
l
a
b
e
l
e
d
po
i
n
t
x.
T
h
e
n
r
e
t
u
r
n
t
o
S
t
e
p
(3
.
1.
2).
(3.
2
.
)
R
e
m
o
v
e
a
l
l
t
h
e
l
a
b
e
l
s
of
t
h
e
n
e
t
w
o
r
k
po
i
n
t
s
,
e
xc
e
pt
f
o
r
t
h
e
s
o
u
r
c
e
po
i
n
t
s
.
R
e
t
urn
t
o
S
t
e
p
(2)
.
Evaluation Warning : The document was created with Spire.PDF for Python.
Int
J
E
l
e
c
&
Co
m
p
E
n
g
IS
S
N
:
2088
-
8708
E
x
t
e
nd
e
d
ne
t
w
or
k
and
a
l
gor
i
t
hm
f
i
nd
i
ng
m
ax
i
m
al
f
l
ow
s
(
T
r
a
n
Ngo
c
V
i
e
t
)
1635
4.
2
.
S
i
n
k
to
w
ar
d
s
o
u
r
c
e
al
go
r
i
th
m
In
p
ut
:
G
i
v
e
n
a
n
e
xt
e
nde
d
n
e
t
w
o
r
k
=
(
,
,
,
)
,
a
s
o
ur
c
e
po
i
n
t
s
a
n
d
a
s
i
n
k
po
i
nt
t
.
T
h
e
po
i
nt
s
i
n
gra
p
h
G
a
r
e
a
rra
nge
d
i
n
a
c
e
rt
a
i
n
o
r
de
r
[3]
.
O
ut
put
:
M
a
xi
m
a
l
f
l
o
w
=
{
(
,
)
|
(
,
)
}
.
(1)
S
t
a
r
t
:
T
h
e
de
pa
rt
u
r
e
f
l
o
w
:
(
,
)
:
=
0
,
(
,
)
.
P
o
i
n
t
s
f
r
o
m
t
h
e
s
i
n
k
po
i
n
t
s
w
i
l
l
g
r
a
du
a
l
l
y
be
l
a
b
e
l
l
e
d
L
1
f
o
r
t
h
e
f
i
r
s
t
t
i
m
e
i
n
c
l
ud
i
n
g
5
c
o
m
po
n
e
n
t
s
:
F
o
r
m
b
a
c
kw
a
r
d
l
a
b
e
l
L1
(
v
)
=
[
,
pr
e
v
1
(
v
),
c
1
(
v
),
d
1
(
v
)
,
b
i
t
1
(
v
)]
a
n
d
c
a
n
b
e
l
a
b
e
l
)
(
f
o
r
t
h
e
s
e
c
o
n
d
t
i
m
e
L2
(
v
)
=
(
v
)
=
[
,
pr
e
v
2
(
v
)
,
c
2
(
v
)
,
d
2
(
v
),
bi
t
2
(
v
)]
.
P
ut
l
a
b
e
l
i
n
g
)
(
f
o
r
s
i
nk
po
i
n
t
:
,
1
]
,
,
,
[
(
t
)
L
1
t
h
e
s
e
t
T
c
o
m
pri
s
e
s
t
h
e
po
i
nt
s
w
hi
c
h
ha
v
e
a
l
r
e
a
dy
be
e
n
l
a
b
e
l
l
e
d
)
(
b
ut
a
r
e
n
o
t
us
e
d
t
o
l
a
b
e
l
)
(
,
T’
i
s
t
h
e
po
i
nt
s
e
t
l
a
b
e
l
l
e
d
)
(
b
a
s
e
d
o
n
t
h
e
po
i
n
t
s
o
f
t
h
e
s
e
t
T
.
B
e
gi
n
(2)
B
a
c
kw
a
r
d
l
a
b
e
l
ge
n
e
r
a
t
e
:
(2.
1)
C
h
o
o
s
e
b
a
c
k
w
a
r
d
l
a
b
e
l
po
i
n
t
:
Ca
s
e
T
:
C
h
o
o
s
e
t
h
e
po
i
nt
o
f
a
m
i
ni
m
u
m
v
a
l
ue
.
R
e
m
ov
e
t
h
e
v
f
r
o
m
t
h
e
s
e
t
T
,
:
=
\
{
}
.
A
s
s
um
i
ng
t
h
a
t
t
h
e
b
a
c
kw
a
r
d
l
a
b
e
l
o
f
v
is
[
,
(
)
,
(
)
,
(
)
,
(
)
]
,
=
1
2
.
B
i
s
t
h
e
s
e
t
o
f
t
h
e
po
i
nt
s
w
h
i
c
h
a
r
e
n
o
t
b
a
c
kw
a
r
d
l
a
b
e
l
t
i
m
e
a
n
d
a
dj
a
c
e
n
t
t
o
t
h
e
b
a
c
kw
a
r
d
l
a
b
e
l
po
i
n
t
v
.
S
t
e
p
(2.
2).
T
'
T
:
:
'
,
'
:
T
T
T
.
R
e
t
urn
t
o
s
t
e
p
(2.
1
).
=
∅
′
=
∅
:
T
h
e
f
l
ow
F
i
s
t
h
e
m
a
x
i
m
u
m
.
E
n
d
.
(2.
2)
B
a
c
kw
a
r
d
l
a
b
e
l
t
h
e
po
i
n
t
s
w
h
i
c
h
a
r
e
n
o
t
b
a
c
kw
a
r
d
l
a
b
e
l
a
n
d
a
r
e
a
dj
a
c
e
n
t
t
o
t
h
e
b
a
c
kw
a
r
d
l
a
b
e
l
po
i
n
t
s
v
Ca
s
e
B
:
R
e
t
u
rn
t
o
S
t
e
p
(2
.
1)
.
Ca
s
e
B
:
C
h
o
o
s
e
o
f
a
m
i
n
i
m
u
m
v
a
l
ue
.
R
e
m
o
ve
t
h
e
t
f
r
o
m
t
h
e
s
e
t
B
,
t
B
B
\
:
.
A
s
s
i
gn
b
a
c
kw
a
r
d
l
a
b
e
l
e
d
po
i
n
t
t
:
If
1
)
(
),
,
(
)
,
(
,
)
,
(
v
b
i
t
v
t
c
v
t
f
E
v
t
i
E
put
b
a
c
kw
a
r
d
l
a
b
e
l
po
i
n
t
t
:
pr
e
v
_j
(t
)
∶
=
v
;
(
)
∶
=
;
(
)
:
=
{
(
)
,
(
,
)
(
,
)
}
,
(
)
=
0
,
(
)
:
=
{
(
)
,
(
,
)
(
,
)
,
(
)
}
,
(
)
>
0
;
(
)
≔
(
)
−
∑
(
,
)
(
,
)
∈
.
(
)
:
=
1
,
(
)
>
0
,
(
)
:
=
0
,
(
)
=
0
.
If
0
)
,
(
,
)
,
(
t
v
f
E
t
v
,
pu
t
b
a
c
kw
a
r
d
l
a
b
e
l
po
i
n
t
t
:
(
)
∶
=
;
(
)
:
=
{
(
)
,
(
,
)
}
,
(
)
≔
(
)
−
∑
(
,
)
(
,
)
∈
;
(
)
≔
1
.
If
t
i
s
n
o
t
b
a
c
kw
a
r
d
l
a
b
e
l
,
t
h
e
n
r
e
t
u
rn
t
o
S
t
e
p
(2.
2).
Evaluation Warning : The document was created with Spire.PDF for Python.
IS
S
N
:
2088
-
8708
Int
J
E
l
e
c
&
Co
m
p
E
n
g
,
V
o
l
.
10
,
N
o
.
2
,
A
p
ri
l
2020
:
1632
-
1640
16
36
If
t
i
s
b
a
c
kw
a
r
d
l
a
b
e
l
a
n
d
t
i
s
f
o
r
w
a
r
d
l
a
b
e
l
,
t
h
e
n
m
a
k
i
n
g
a
dj
us
t
m
e
n
t
s
i
n
i
n
c
r
e
a
s
e
o
f
t
h
e
f
l
o
w
.
S
t
e
p
(3)
.
If
t
i
s
b
a
c
kw
a
r
d
l
a
b
e
l
a
nd
t
i
s
n
o
t
f
o
r
w
a
r
d
l
a
b
e
l
,
t
h
e
n
a
dd
t
t
o
T’
,
T’
:=
T’
{
t
}
,
a
n
d
r
e
t
u
rn
t
o
S
t
e
p
(2
.
2)
.
(3)
M
a
ki
n
g
a
dj
us
t
m
e
n
t
s
i
n
i
n
c
r
e
a
s
e
o
f
t
h
e
f
l
o
w
:
S
uppo
s
e
t
i
s
b
a
c
kw
a
r
d
l
a
b
e
l
[
,
(
)
,
(
)
,
(
)
,
(
)
]
(3.
1)
A
dj
us
t
m
e
n
t
m
a
de
f
r
o
m
v
t
o
t
a
c
c
o
r
di
n
g
t
o
b
a
c
kw
a
r
d
l
a
b
e
l
(3.
1
.
1)
S
t
a
rt
∶
=
,
∶
=
1
(
)
,
∶
=
1
(
)
.
(3.
1
.
2)
M
a
k
i
n
g
a
dj
us
t
m
e
nt
s
(i
)
C
a
s
e
(
,
)
t
h
e
r
o
a
d
s
e
c
t
i
o
n
w
h
o
s
e
di
r
e
c
t
i
o
n
r
u
n
s
f
r
o
m
x
t
o
y
:
put
(
,
)
∶
=
(
,
)
+
.
(i
i
)
Ca
s
e
(
,
)
t
h
e
r
o
a
d
s
e
c
t
i
o
n
w
h
o
s
e
di
r
e
c
t
i
o
n
ru
n
s
f
r
o
m
y
t
o
x
:
put
(
,
)
:
=
(
,
)
.
(i
i
i
)
C
a
s
e
(
,
)
n
o
n
-
d
i
r
e
c
t
i
o
n
r
o
a
ds
:
If
(
,
)
0
(
,
)
=
0
t
h
e
n
put
(
,
)
∶
=
(
,
)
+
.
If
(
,
)
>
0
t
h
e
n
put
(
,
)
∶
=
(
,
)
.
(3.
1
.
3)
M
o
v
i
n
g
(i
)
C
a
s
e
=
.
S
t
e
p
(3
.
2)
.
(i
i
)
Ca
s
e
,
∶
=
:
=
,
i
s
t
h
e
s
e
c
o
n
d
c
o
m
po
n
e
n
t
o
f
t
h
e
b
a
c
kw
a
r
d
l
a
b
e
l
e
d
po
i
n
t
x
.
T
h
e
n
r
e
t
u
rn
t
o
s
t
e
p
(3
.
1.
2).
(3.
2)
R
e
m
ov
e
a
l
l
t
h
e
l
a
b
e
l
s
o
f
t
h
e
n
e
t
w
o
r
k
po
i
nt
s
,
e
xc
e
pt
f
o
r
t
h
e
s
i
n
k
po
i
n
t
t
.
R
e
t
u
rn
t
o
S
t
e
p
(
2).
4.
3
.
Th
e
o
r
e
m
2
If
t
h
e
v
a
l
ue
o
f
t
h
e
r
o
ut
e
c
i
r
c
ul
a
t
i
o
n
po
s
s
i
b
i
l
i
t
y
a
n
d
t
h
e
c
i
r
c
l
e
c
i
r
c
ul
a
t
i
o
n
po
s
s
i
b
i
l
i
t
y
a
r
e
i
nt
e
ge
r
s
,
t
h
e
n
a
f
t
e
r
a
l
i
m
i
t
e
d
n
u
m
b
e
r
o
f
s
t
e
ps
,
t
h
e
p
r
o
c
e
s
s
i
n
g
o
f
t
h
e
m
a
xi
m
um
n
e
t
w
o
r
k
p
r
o
b
l
e
m
w
i
l
l
e
n
d.
P
r
oof
A
c
c
o
r
di
n
g
t
o
t
h
e
o
r
e
m
1,
a
f
t
e
r
e
a
c
h
t
i
m
e
o
f
m
a
ki
ng
a
dj
us
t
m
e
nt
o
f
t
h
e
f
l
o
w
,
t
h
e
f
l
o
w
w
i
l
l
b
e
i
n
c
r
e
a
s
e
d
w
i
t
h
c
e
rt
a
i
n
u
ni
t
s
(due
t
o
c
E
i
s
a
w
h
o
l
e
num
b
e
r,
c
V
i
s
a
w
ho
l
e
n
um
b
e
r,
a
nd
δ
i
s
,
t
h
e
r
e
f
o
r
e
,
a
po
s
i
t
i
v
e
w
h
o
l
e
n
u
m
b
e
r
).
O
n
t
h
e
o
t
h
e
r
h
a
nd,
t
h
e
v
a
l
ue
o
f
t
h
e
f
l
ow
i
s
l
i
m
i
t
e
d
a
b
ov
e
by
t
h
e
t
o
t
a
l
a
m
o
unt
o
f
t
h
e
c
i
r
c
ul
a
t
i
o
n
po
s
s
i
b
i
l
i
t
y
a
t
r
o
a
ds
l
e
a
v
i
n
g
t
h
e
s
o
ur
c
e
po
i
nt
s
.
S
o
,
a
f
t
e
r
a
l
i
m
i
t
e
d
n
u
m
b
e
r
o
f
s
t
e
ps
,
t
h
e
p
r
o
c
e
s
s
i
n
g
o
f
t
h
e
m
a
x
i
m
u
m
n
e
t
w
o
r
k
p
r
o
b
l
e
m
w
i
l
l
e
n
d
.
4.
4
.
Th
e
o
r
e
m
3
G
i
v
e
n
a
n
=
{
(
,
)
|
(
,
)
}
i
s
t
h
e
f
l
o
w
o
n
e
xt
e
n
de
d
n
e
t
w
o
r
k
G
,
a
s
o
ur
c
e
po
i
nt
s
a
n
d
a
s
i
nk
po
i
n
t
t
:
E
t
x
E
x
s
t
x
f
x
s
f
)
,
(
)
,
(
,
,
(5)
P
r
oof
T
h
e
po
i
n
t
s
o
f
t
h
e
s
e
t
V
.
If
x,
y
i
s
n
o
t
p
r
e
v
i
o
us
,
a
s
s
i
g
n
0
)
,
(
y
x
f
V
y
V
x
V
y
V
x
x
y
f
y
x
f
)
,
(
)
,
(
0
)
,
(
)
,
(
V
y
V
x
V
x
x
y
f
y
x
f
E
t
x
E
x
s
E
t
x
E
x
s
t
x
f
x
s
f
t
x
f
x
s
f
)
,
(
)
,
(
)
,
(
)
,
(
,
,
0
,
,
.
Evaluation Warning : The document was created with Spire.PDF for Python.
Int
J
E
l
e
c
&
Co
m
p
E
n
g
IS
S
N
:
2088
-
8708
E
x
t
e
nd
e
d
ne
t
w
or
k
and
a
l
gor
i
t
hm
f
i
nd
i
ng
m
ax
i
m
al
f
l
ow
s
(
T
r
a
n
Ngo
c
V
i
e
t
)
1637
4.
5
.
Th
e
c
o
m
p
l
e
x
i
ty
o
f
th
e
al
go
r
i
th
m
It
i
s
a
s
s
um
e
d
t
ha
t
t
h
e
r
o
a
d
c
i
r
c
ul
a
t
i
o
n
po
s
s
i
b
i
l
i
t
y
a
n
d
t
h
e
po
i
n
t
c
i
r
c
ul
a
t
i
o
n
po
s
s
i
b
i
l
i
t
y
a
r
e
w
h
o
l
e
i
n
t
e
ge
r
.
A
f
t
e
r
e
a
c
h
r
o
und
s
t
e
p,
t
o
f
i
n
d
t
h
e
r
o
a
ds
t
o
i
n
c
r
e
a
s
e
t
h
e
a
m
o
unt
o
f
c
i
r
c
ul
a
t
i
o
n
o
n
t
h
e
f
l
o
w
,
w
e
h
a
v
e
t
o
a
p
p
r
o
ve
t
o
pa
s
s
E
r
o
a
ds
i
n
m
a
xi
m
u
m
,
a
nd
i
n
o
r
de
r
t
o
a
dj
us
t
t
h
e
f
l
ow
w
e
h
a
v
e
t
o
a
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Int
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7]
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11]
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12]
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gor
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s
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l
.
4
,
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.
[
14]
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o
s
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ph
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r
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s
hke
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hl
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on
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h
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ar
t
B
:
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e
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hod
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o
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c
al
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o
l
.
34
,
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.
4
,
2000
.
[
15]
L
uc
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e
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s
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e
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an
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ni
v
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S2
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m
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on
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11.
[
16]
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a
r
dr
o
p,
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.
G
,
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o
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ngs
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ne
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s
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a
r
t
I
I
,
195
2.
[
17]
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l
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nd
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,
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ppr
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as
s
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hus
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t
t
s
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n
s
t
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t
ut
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hn
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o
g
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.
[
18]
J
ua
n
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a
r
l
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s
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uno
z
,
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o
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g
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.
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6.
[
19]
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l
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a
h
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.
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.
53
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4
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5.
[
20]
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21]
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r
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por
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s
R
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ar
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h
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e
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U
C
B
-
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-
RR
,
2002
.
[
22]
Z
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[
23]
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2000
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[
24]
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por
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Sc
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.
12
,
197
8.
[
25]
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