app
x
y
helpa
0
plus
length
x
length
y
x
y
plus
x
0
x
plus
x
s
y
s
plus
x
y
length
nil
0
length
cons
x
y
s
length
y
helpa
c
l
ys
zs
if
ge
c
l
c
l
ys
zs
ge
x
0
true
ge
0
s
x
false
ge
s
x
s
y
ge
x
y
if
true
c
l
ys
zs
nil
if
false
c
l
ys
zs
helpb
c
l
ys
zs
take
0
cons
x
xs
ys
x
take
0
nil
cons
y
ys
y
take
s
c
cons
x
xs
ys
take
c
xs
ys
take
s
c
nil
cons
y
ys
take
c
nil
ys
helpb
c
l
ys
zs
cons
take
c
ys
zs
helpa
s
c
l
ys
zs
2.2
helpa
c
l
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zs
ge
c
l
length
cons
x
y
length
y
app
x
y
length
y
plus
x
s
y
plus
x
y
app
x
y
plus
length
x
length
y
app
x
y
length
x
take
s
c
nil
cons
y
ys
take
c
nil
ys
helpb
c
l
ys
zs
take
c
ys
zs
app
x
y
helpa
0
plus
length
x
length
y
x
y
take
s
c
cons
x
xs
ys
take
c
xs
ys
ge
s
x
s
y
ge
x
y
helpa
c
l
ys
zs
if
ge
c
l
c
l
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zs
helpb
c
l
ys
zs
helpa
s
c
l
ys
zs
if
false
c
l
ys
zs
helpb
c
l
ys
zs
true
app
x
y
length
x
false
app
x
y
plus
length
x
length
y
false
plus
x
s
y
plus
x
y
true
s
1
1
1
take
3
0
take
3
0
plus
2
2
0
helpa
4
0
false
0
0
ge
2
0
helpb
4
0
true
0
0
0
0
0
if
5
0
ge
2
0
nil
0
0
app
2
0
plus
2
0
cons
2
0
if
5
0
xs
0
0
helpa
4
0
length
1
0
length
1
0
helpb
4
0
app
2
0
app
x
y
length
y
false
length
cons
x
y
length
y
true
s
1
1
take
3
0
take
3
0
plus
2
0
helpa
4
0
false
0
0
ge
2
0
helpb
4
0
true
0
0
0
0
0
if
5
0
ge
2
0
nil
0
0
app
2
0
plus
2
0
cons
2
2
1
if
5
0
xs
0
0
helpa
4
0
length
1
0
length
1
1
0
helpb
4
0
app
2
0
app
x
y
helpa
0
plus
length
x
length
y
x
y
false
if
false
c
l
ys
zs
helpb
c
l
ys
zs
helpb
c
l
ys
zs
helpa
s
c
l
ys
zs
helpa
c
l
ys
zs
if
ge
c
l
c
l
ys
zs
true
Failed!
NaTT
certifiable-1.6