ZOJ-不知道是哪道题

August 22, 2004 is Chinese Valentine's Day. popo's girlfriend qoqo asks popo to see beautiful star field with her. qoqo takes a fancy to a lawn at the back-hill. But as popo known, there are some bugs in the lawn. It's a feature that it has bug (-_-). So popo is planning to sprinkle pesticide in advance. And now popo needs your help to calculate how much pesticide needed at least to kill all the bugs on the lawn.August 22, 2004 is Chinese Valentine's D