(VAR m n x y )
(RULES 
        minus(x, 0) -> x
        minus(s(x), s(y)) -> minus(x, y)
        quot(0, s(y)) -> 0
        quot(s(x), s(y)) -> s(quot(minus(x, y), s(y)))
        le(0, y) -> true
        le(s(x), 0) -> false
        le(s(x), s(y)) -> le(x, y)
        app(nil, y) -> y
        app(add(n, x), y) -> add(n, app(x, y))
        low(n, nil) -> nil
        low(n, add(m, x)) -> if_low(le(m, n), n, add(m, x))
        if_low(true, n, add(m, x)) -> add(m, low(n, x))
        if_low(false, n, add(m, x)) -> low(n, x)
        high(n, nil) -> nil
        high(n, add(m, x)) -> if_high(le(m, n), n, add(m, x))
        if_high(true, n, add(m, x)) -> high(n, x)
        if_high(false, n, add(m, x)) -> add(m, high(n, x))
        quicksort(nil) -> nil
        quicksort(add(n, x)) -> app(quicksort(low(n, x)), add(n, quicksort(high(n, x))))
        
)