P3027 [USACO10OCT] Making Money G

FJ又经营起了古董生意，买卖一些像奶牛圣诞树上的装饰之类的小玩意。他知道他会将他能存储的N(1

FJ has gone into the curio business, buying and selling knickknacks like cow Christmas tree ornaments. He knows he will sell every single curio he can stock from a catalog of N (1

\* Line 1: Two space-separated integers: N and M \* Lines 2..N+1: Line i+1 contains two space-separated integers: C\_i and R\_i

\* Line 1: The maximum profit FJ can generate given the costs and revenues