(STRATEGY
    INNERMOST)

(VAR
    x y)
(DATATYPES
    A = µX.< 0, s(X), if(X, X, X), greater(X, X) >)
(SIGNATURES
    - :: [A x A] -> A
    p :: [A] -> A)
(RULES
    -(0(),y) -> 0()
    -(x,0()) -> x
    -(x,s(y)) -> if(greater(x,s(y))
                   ,s(-(x,p(s(y))))
                   ,0())
    p(0()) -> 0()
    p(s(x)) -> x)