+
0
y
y
+
s
x
y
s
+
x
y
++
nil
ys
ys
++
:
x
xs
ys
:
x
++
xs
ys
sum
:
x
nil
:
x
nil
sum
:
x
:
y
xs
sum
:
+
x
y
xs
sum
++
xs
:
x
:
y
ys
sum
++
xs
sum
:
x
:
y
ys
-
x
0
x
-
0
s
y
0
-
s
x
s
y
-
x
y
quot
0
s
y
0
quot
s
x
s
y
s
quot
-
x
y
s
y
length
nil
0
length
:
x
xs
s
length
xs
hd
:
x
xs
x
avg
xs
quot
hd
sum
xs
length
xs
+
2
0
0
s
1
++
2
nil
0
:
2
sum
1
-
2
quot
2
length
1
hd
1
avg
1
FULL
./TRS/various/10.trs