r
xs
ys
zs
nil
xs
r
xs
nil
zs
cons
w
ws
r
xs
xs
cons
succ
zero
zs
ws
r
xs
cons
y
ys
nil
cons
w
ws
r
xs
xs
cons
succ
zero
nil
ws
r
xs
cons
y
ys
cons
z
zs
cons
w
ws
r
ys
cons
y
ys
zs
cons
succ
zero
cons
w
ws
2.2
r
xs
cons
y
ys
nil
cons
w
ws
r
xs
xs
cons
succ
zero
nil
ws
r
xs
cons
y
ys
cons
z
zs
cons
w
ws
r
ys
cons
y
ys
zs
cons
succ
zero
cons
w
ws
r
xs
nil
zs
cons
w
ws
r
xs
xs
cons
succ
zero
zs
ws
true
r
xs
nil
zs
cons
w
ws
r
xs
xs
cons
succ
zero
zs
ws
r
xs
cons
y
ys
cons
z
zs
cons
w
ws
r
ys
cons
y
ys
zs
cons
succ
zero
cons
w
ws
r
xs
cons
y
ys
nil
cons
w
ws
r
xs
xs
cons
succ
zero
nil
ws
true
Failed!
NaTT
certifiable-1.6