(VAR c x y )
(RULES 
        times(x, y) -> help(x, y, 0)
        help(x, y, c) -> if(lt(c, y), x, y, c)
        if(true, x, y, c) -> plus(x, help(x, y, s(c)))
        if(false, x, y, c) -> 0
        lt(0, s(x)) -> true
        lt(s(x), 0) -> false
        lt(s(x), s(y)) -> lt(x, y)
        plus(x, 0) -> x
        plus(0, x) -> x
        plus(x, s(y)) -> s(plus(x, y))
        plus(s(x), y) -> s(plus(x, y))
        
)