active
and
true
X
mark
X
active
and
false
Y
mark
false
active
if
true
X
Y
mark
X
active
if
false
X
Y
mark
Y
active
add
0
X
mark
X
active
add
s
X
Y
mark
s
add
X
Y
active
first
0
X
mark
nil
active
first
s
X
cons
Y
Z
mark
cons
Y
first
X
Z
active
from
X
mark
cons
X
from
s
X
active
and
X1
X2
and
active
X1
X2
active
if
X1
X2
X3
if
active
X1
X2
X3
active
add
X1
X2
add
active
X1
X2
active
first
X1
X2
first
active
X1
X2
active
first
X1
X2
first
X1
active
X2
and
mark
X1
X2
mark
and
X1
X2
if
mark
X1
X2
X3
mark
if
X1
X2
X3
add
mark
X1
X2
mark
add
X1
X2
first
mark
X1
X2
mark
first
X1
X2
first
X1
mark
X2
mark
first
X1
X2
proper
and
X1
X2
and
proper
X1
proper
X2
proper
true
ok
true
proper
false
ok
false
proper
if
X1
X2
X3
if
proper
X1
proper
X2
proper
X3
proper
add
X1
X2
add
proper
X1
proper
X2
proper
0
ok
0
proper
s
X
s
proper
X
proper
first
X1
X2
first
proper
X1
proper
X2
proper
nil
ok
nil
proper
cons
X1
X2
cons
proper
X1
proper
X2
proper
from
X
from
proper
X
and
ok
X1
ok
X2
ok
and
X1
X2
if
ok
X1
ok
X2
ok
X3
ok
if
X1
X2
X3
add
ok
X1
ok
X2
ok
add
X1
X2
s
ok
X
ok
s
X
first
ok
X1
ok
X2
ok
first
X1
X2
cons
ok
X1
ok
X2
ok
cons
X1
X2
from
ok
X
ok
from
X
top
mark
X
top
proper
X
top
ok
X
top
active
X
active
1
and
2
true
0
mark
1
false
0
if
3
add
2
0
0
s
1
first
2
nil
0
cons
2
from
1
proper
1
ok
1
top
1
FULL
./TRS/TRCSR/Ex15_Luc98_C.trs