active
zeros
mark
cons
0
zeros
active
and
tt
X
mark
X
active
length
nil
mark
0
active
length
cons
N
L
mark
s
length
L
active
cons
X1
X2
cons
active
X1
X2
active
and
X1
X2
and
active
X1
X2
active
length
X
length
active
X
active
s
X
s
active
X
cons
mark
X1
X2
mark
cons
X1
X2
and
mark
X1
X2
mark
and
X1
X2
length
mark
X
mark
length
X
s
mark
X
mark
s
X
proper
zeros
ok
zeros
proper
cons
X1
X2
cons
proper
X1
proper
X2
proper
0
ok
0
proper
and
X1
X2
and
proper
X1
proper
X2
proper
tt
ok
tt
proper
length
X
length
proper
X
proper
nil
ok
nil
proper
s
X
s
proper
X
cons
ok
X1
ok
X2
ok
cons
X1
X2
and
ok
X1
ok
X2
ok
and
X1
X2
length
ok
X
ok
length
X
s
ok
X
ok
s
X
top
mark
X
top
proper
X
top
ok
X
top
active
X
2.2
active
and
X1
X2
active
X1
active
s
X
active
X
length
ok
X
length
X
proper
s
X
s
proper
X
proper
cons
X1
X2
proper
X1
top
mark
X
top
proper
X
proper
and
X1
X2
and
proper
X1
proper
X2
cons
ok
X1
ok
X2
cons
X1
X2
top
mark
X
proper
X
active
length
cons
N
L
length
L
proper
s
X
proper
X
active
length
cons
N
L
s
length
L
proper
and
X1
X2
proper
X1
and
ok
X1
ok
X2
and
X1
X2
s
mark
X
s
X
proper
cons
X1
X2
proper
X2
proper
length
X
proper
X
s
ok
X
s
X
active
s
X
s
active
X
top
ok
X
active
X
active
zeros
cons
0
zeros
and
mark
X1
X2
and
X1
X2
proper
length
X
length
proper
X
active
cons
X1
X2
active
X1
proper
and
X1
X2
proper
X2
top
ok
X
top
active
X
active
length
X
active
X
cons
mark
X1
X2
cons
X1
X2
active
and
X1
X2
and
active
X1
X2
proper
cons
X1
X2
cons
proper
X1
proper
X2
active
length
X
length
active
X
length
mark
X
length
X
active
cons
X1
X2
cons
active
X1
X2
true
top
ok
X
top
active
X
top
mark
X
top
proper
X
true
Failed!
NaTT
certifiable-1.6