1685 - [Usaco2005 Oct]Allowance 津贴

As a reward for record milk production, Farmer John has decided to start paying Bessie the cow a small weekly allowance. FJ has a set of coins in N (1 <= N <= 20) different denominations, where each denomination of coin evenly divides the next-larger denomination (e.g., 1 cent coins, 5 cent coins, 10 cent coins, and 50 cent coins). Using the given set of coins, he would like to pay Bessie at least some given amount of money C (1 <= C <= 100,000,000) every week. Please help him compute the maximum number of weeks he can pay Bessie. 作为对勤勤恳恳工作的贝茜的奖励，约翰已经决定开始支付贝茜一个小的每周津贴． 约翰有n(1≤N≤20)种币值的硬币，面值小的硬币总能整除面值较大的硬币．比如说，币值有如下几种：1美分，5美分，10美分，50美分…．．

利用给定的这些硬币，他将要每周付给贝茜一定金额的津贴C(1≤C≤10^8)．
请帮他计算出他最多能给贝茜发几周的津贴．

第1行：2个用空格隔开的整数n和C.
第2到n+1行：每行两个整数表示一种币值的硬币．第一个整数V(I≤y≤10^8)，表示币值．

第二个整数B(1≤B≤10^6)，表示约翰拥有的这种硬币的个数．

一个整数，表示约翰付给贝茜津贴得最多的周数．