qsort
xs
qs
half
length
xs
xs
qs
n
nil
nil
qs
n
cons
x
xs
append
qs
half
n
filterlow
get
n
cons
x
xs
cons
x
xs
cons
get
n
cons
x
xs
qs
half
n
filterhigh
get
n
cons
x
xs
cons
x
xs
filterlow
n
nil
nil
filterlow
n
cons
x
xs
if1
ge
n
x
n
x
xs
if1
true
n
x
xs
filterlow
n
xs
if1
false
n
x
xs
cons
x
filterlow
n
xs
filterhigh
n
nil
nil
filterhigh
n
cons
x
xs
if2
ge
x
n
n
x
xs
if2
true
n
x
xs
filterhigh
n
xs
if2
false
n
x
xs
cons
x
filterhigh
n
xs
ge
x
0
true
ge
0
s
x
false
ge
s
x
s
y
ge
x
y
append
nil
ys
ys
append
cons
x
xs
ys
cons
x
append
xs
ys
length
nil
0
length
cons
x
xs
s
length
xs
half
0
0
half
s
0
0
half
s
s
x
s
half
x
get
n
nil
0
get
n
cons
x
nil
x
get
0
cons
x
cons
y
xs
x
get
s
n
cons
x
cons
y
xs
get
n
cons
y
xs
2.2
filterhigh
n
cons
x
xs
if2
ge
x
n
n
x
xs
get
s
n
cons
x
cons
y
xs
get
n
cons
y
xs
qs
n
cons
x
xs
append
qs
half
n
filterlow
get
n
cons
x
xs
cons
x
xs
cons
get
n
cons
x
xs
qs
half
n
filterhigh
get
n
cons
x
xs
cons
x
xs
filterlow
n
cons
x
xs
if1
ge
n
x
n
x
xs
half
s
s
x
half
x
qsort
xs
half
length
xs
qsort
xs
qs
half
length
xs
xs
append
cons
x
xs
ys
append
xs
ys
qs
n
cons
x
xs
qs
half
n
filterlow
get
n
cons
x
xs
cons
x
xs
qsort
xs
length
xs
qs
n
cons
x
xs
half
n
if1
false
n
x
xs
filterlow
n
xs
filterlow
n
cons
x
xs
ge
n
x
ge
s
x
s
y
ge
x
y
qs
n
cons
x
xs
get
n
cons
x
xs
qs
n
cons
x
xs
get
n
cons
x
xs
qs
n
cons
x
xs
qs
half
n
filterhigh
get
n
cons
x
xs
cons
x
xs
length
cons
x
xs
length
xs
qs
n
cons
x
xs
filterhigh
get
n
cons
x
xs
cons
x
xs
qs
n
cons
x
xs
filterlow
get
n
cons
x
xs
cons
x
xs
filterhigh
n
cons
x
xs
ge
x
n
if1
true
n
x
xs
filterlow
n
xs
if2
true
n
x
xs
filterhigh
n
xs
qs
n
cons
x
xs
half
n
if2
false
n
x
xs
filterhigh
n
xs
qs
n
cons
x
xs
get
n
cons
x
xs
true
qsort
xs
length
xs
false
append
cons
x
xs
ys
append
xs
ys
true
qs
2
0
s
1
0
append
2
1
0
if1
4
0
false
0
0
ge
2
0
filterlow
2
0
half
1
0
qsort
1
0
true
0
0
if1
4
0
half
1
0
if2
4
0
qsort
1
0
qs
2
0
append
2
0
0
0
0
ge
2
0
nil
0
0
filterlow
2
0
get
2
0
get
2
0
cons
2
2
1
filterhigh
2
0
ys
0
0
filterhigh
2
0
length
1
0
if2
4
0
length
1
0
qsort
xs
qs
half
length
xs
xs
false
qsort
xs
half
length
xs
false
length
cons
x
xs
length
xs
true
qs
2
0
s
1
0
append
2
0
if1
4
0
false
0
0
ge
2
0
filterlow
2
0
half
1
0
qsort
1
0
true
0
0
if1
4
0
half
1
0
if2
4
0
qsort
1
0
qs
2
0
append
2
0
0
0
0
ge
2
0
nil
0
0
filterlow
2
0
get
2
0
get
2
0
cons
2
2
1
filterhigh
2
0
ys
0
0
filterhigh
2
0
length
1
0
if2
4
0
length
1
1
0
qs
n
cons
x
xs
qs
half
n
filterlow
get
n
cons
x
xs
cons
x
xs
qs
n
cons
x
xs
qs
half
n
filterhigh
get
n
cons
x
xs
cons
x
xs
true
Failed!
NaTT
certifiable-1.6