from
X
cons
X
n__from
s
X
length
n__nil
0
length
n__cons
X
Y
s
length1
activate
Y
length1
X
length
activate
X
from
X
n__from
X
nil
n__nil
cons
X1
X2
n__cons
X1
X2
activate
n__from
X
from
X
activate
n__nil
nil
activate
n__cons
X1
X2
cons
X1
X2
activate
X
X
2.2
activate
n__cons
X1
X2
cons
X1
X2
activate
n__from
X
from
X
length1
X
length
activate
X
from
X
cons
X
n__from
s
X
length
n__cons
X
Y
length1
activate
Y
activate
n__nil
nil
length1
X
activate
X
length
n__cons
X
Y
activate
Y
true
length
n__cons
X
Y
length1
activate
Y
length1
X
length
activate
X
true
Failed!
NaTT
certifiable-1.6