(VAR L X X1 X2 XS Y YS )
(RULES 
        active(app(nil, YS)) -> mark(YS)
        active(app(cons(X, XS), YS)) -> mark(cons(X, app(XS, YS)))
        active(from(X)) -> mark(cons(X, from(s(X))))
        active(zWadr(nil, YS)) -> mark(nil)
        active(zWadr(XS, nil)) -> mark(nil)
        active(zWadr(cons(X, XS), cons(Y, YS))) -> mark(cons(app(Y, cons(X, nil)), zWadr(XS, YS)))
        active(prefix(L)) -> mark(cons(nil, zWadr(L, prefix(L))))
        mark(app(X1, X2)) -> active(app(mark(X1), mark(X2)))
        mark(nil) -> active(nil)
        mark(cons(X1, X2)) -> active(cons(mark(X1), X2))
        mark(from(X)) -> active(from(mark(X)))
        mark(s(X)) -> active(s(mark(X)))
        mark(zWadr(X1, X2)) -> active(zWadr(mark(X1), mark(X2)))
        mark(prefix(X)) -> active(prefix(mark(X)))
        app(mark(X1), X2) -> app(X1, X2)
        app(X1, mark(X2)) -> app(X1, X2)
        app(active(X1), X2) -> app(X1, X2)
        app(X1, active(X2)) -> app(X1, X2)
        cons(mark(X1), X2) -> cons(X1, X2)
        cons(X1, mark(X2)) -> cons(X1, X2)
        cons(active(X1), X2) -> cons(X1, X2)
        cons(X1, active(X2)) -> cons(X1, X2)
        from(mark(X)) -> from(X)
        from(active(X)) -> from(X)
        s(mark(X)) -> s(X)
        s(active(X)) -> s(X)
        zWadr(mark(X1), X2) -> zWadr(X1, X2)
        zWadr(X1, mark(X2)) -> zWadr(X1, X2)
        zWadr(active(X1), X2) -> zWadr(X1, X2)
        zWadr(X1, active(X2)) -> zWadr(X1, X2)
        prefix(mark(X)) -> prefix(X)
        prefix(active(X)) -> prefix(X)
        
)