(VAR x y z)
(RULES
minus(x,0) -> x
minus(0,y) -> 0
minus(s(x),s(y)) -> minus(p(s(x)),p(s(y)))
minus(x,plus(y,z))-> minus(minus(x,y),z)
p(s(s(x))) -> s(p(s(x)))
p(0) -> s(s(0))
div(s(x),s(y)) -> s(div(minus(x,y),s(y)))
div(plus(x,y),z) -> plus(div(x,z),div(y,z))
plus(0,y) -> y
plus(s(x),y) -> s(plus(y,minus(s(x),s(0))))
)