a
a
divides
0
a
s
y
true
a
a
divides
a
s
x
a
s
y
a
a
a
div2
x
a
s
y
y
a
a
a
div2
x
y
0
a
a
divides
x
y
a
a
a
div2
0
y
a
s
z
false
a
a
a
div2
a
s
x
y
a
s
z
a
a
a
div2
x
y
z
a
a
filter
f
nil
nil
a
a
filter
f
a
a
cons
x
xs
a
a
a
if
a
f
x
x
a
a
filter
f
xs
a
a
a
if
true
x
xs
a
a
cons
x
xs
a
a
a
if
false
x
xs
xs
a
a
not
f
x
a
not2
a
f
x
a
not2
true
false
a
not2
false
true
a
sieve
nil
nil
a
sieve
a
a
cons
x
xs
a
a
cons
x
a
sieve
a
a
filter
a
not
a
divides
x
xs
2.2
a
a
divides
a
s
x
a
s
y
a
a
div2
x
a
s
y
a
sieve
a
a
cons
x
xs
a
a
filter
a
not
a
divides
x
xs
a
a
filter
f
a
a
cons
x
xs
a
f
x
a
sieve
a
a
cons
x
xs
a
divides
x
a
a
filter
f
a
a
cons
x
xs
a
a
if
a
f
x
x
a
a
a
if
true
x
xs
a
cons
x
a
a
filter
f
a
a
cons
x
xs
a
if
a
f
x
a
a
filter
f
a
a
cons
x
xs
a
a
filter
f
xs
a
a
a
div2
x
y
0
a
a
divides
x
y
a
sieve
a
a
cons
x
xs
a
filter
a
not
a
divides
x
a
a
filter
f
a
a
cons
x
xs
a
a
a
if
a
f
x
x
a
a
filter
f
xs
a
sieve
a
a
cons
x
xs
a
sieve
a
a
filter
a
not
a
divides
x
xs
a
a
a
if
true
x
xs
a
a
cons
x
xs
a
a
a
div2
a
s
x
y
a
s
z
a
a
a
div2
x
y
z
a
a
a
div2
a
s
x
y
a
s
z
a
div2
x
a
a
a
div2
x
y
0
a
divides
x
a
a
not
f
x
a
f
x
a
a
divides
a
s
x
a
s
y
a
div2
x
a
a
divides
a
s
x
a
s
y
a
a
a
div2
x
a
s
y
y
a
sieve
a
a
cons
x
xs
a
not
a
divides
x
a
a
not
f
x
a
not2
a
f
x
a
sieve
a
a
cons
x
xs
a
a
cons
x
a
sieve
a
a
filter
a
not
a
divides
x
xs
a
a
a
div2
a
s
x
y
a
s
z
a
a
div2
x
y
true
a
a
filter
f
a
a
cons
x
xs
a
a
filter
f
xs
a
a
not
f
x
a
f
x
a
a
filter
f
a
a
cons
x
xs
a
f
x
a
sieve
a
a
cons
x
xs
a
a
filter
a
not
a
divides
x
xs
a
sieve
a
a
cons
x
xs
a
sieve
a
a
filter
a
not
a
divides
x
xs
true
Failed!
NaTT
certifiable-1.6