(VAR N X X1 X2 XS Y YS )
(RULES 
        active(pairNs) -> mark(cons(0, incr(oddNs)))
        active(oddNs) -> mark(incr(pairNs))
        active(incr(cons(X, XS))) -> mark(cons(s(X), incr(XS)))
        active(take(0, XS)) -> mark(nil)
        active(take(s(N), cons(X, XS))) -> mark(cons(X, take(N, XS)))
        active(zip(nil, XS)) -> mark(nil)
        active(zip(X, nil)) -> mark(nil)
        active(zip(cons(X, XS), cons(Y, YS))) -> mark(cons(pair(X, Y), zip(XS, YS)))
        active(tail(cons(X, XS))) -> mark(XS)
        active(repItems(nil)) -> mark(nil)
        active(repItems(cons(X, XS))) -> mark(cons(X, cons(X, repItems(XS))))
        mark(pairNs) -> active(pairNs)
        mark(cons(X1, X2)) -> active(cons(mark(X1), X2))
        mark(0) -> active(0)
        mark(incr(X)) -> active(incr(mark(X)))
        mark(oddNs) -> active(oddNs)
        mark(s(X)) -> active(s(mark(X)))
        mark(take(X1, X2)) -> active(take(mark(X1), mark(X2)))
        mark(nil) -> active(nil)
        mark(zip(X1, X2)) -> active(zip(mark(X1), mark(X2)))
        mark(pair(X1, X2)) -> active(pair(mark(X1), mark(X2)))
        mark(tail(X)) -> active(tail(mark(X)))
        mark(repItems(X)) -> active(repItems(mark(X)))
        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)
        incr(mark(X)) -> incr(X)
        incr(active(X)) -> incr(X)
        s(mark(X)) -> s(X)
        s(active(X)) -> s(X)
        take(mark(X1), X2) -> take(X1, X2)
        take(X1, mark(X2)) -> take(X1, X2)
        take(active(X1), X2) -> take(X1, X2)
        take(X1, active(X2)) -> take(X1, X2)
        zip(mark(X1), X2) -> zip(X1, X2)
        zip(X1, mark(X2)) -> zip(X1, X2)
        zip(active(X1), X2) -> zip(X1, X2)
        zip(X1, active(X2)) -> zip(X1, X2)
        pair(mark(X1), X2) -> pair(X1, X2)
        pair(X1, mark(X2)) -> pair(X1, X2)
        pair(active(X1), X2) -> pair(X1, X2)
        pair(X1, active(X2)) -> pair(X1, X2)
        tail(mark(X)) -> tail(X)
        tail(active(X)) -> tail(X)
        repItems(mark(X)) -> repItems(X)
        repItems(active(X)) -> repItems(X)
        
)