Answer: ironic understatement in which an affirmative is expressed by the negative of its contrary (e.g., you won't be sorry, meaning you'll be glad )
Explanation: In truth, a litotes will use irony to emphasize an idea without minimizing its importance. For example, a friend might expect her roommate to talk about someone who's obviously wealthy by saying, “He's filthy rich.” However, when she comes out and says, “Well, he's not exactly a pauper,” it's a little unexpected.