(VAR x y z )
(STRATEGY INNERMOST)
(RULES 
        f(cons(nil,y)) -> y
        f(cons(f(cons(nil,y)),z)) -> copy(n,y,z)
        copy(0,y,z) -> f(z)
        copy(s(x),y,z) -> copy(x,y,cons(f(y),z))
        
)