THEM: i need the ball and hat  YOU: i need the ball or we can't reach an agreement. try a better offer,  THEM: guess we cant deal..... books have zero value to me  YOU: the ball is essential or i will not reach my target.  THEM: same here  YOU: how about you give me the ball and you take everything else  THEM: books still have a zero value on my side......  YOU: the hat wont get you by?  THEM: no  YOU: i guess we can't make a deal then.