最小钱币数：这是一个古老而又经典的问题。用给定的几种钱币凑成某个钱数，一般而言有多种方式。例如：给定了6种钱币面值为2、5、10、20、50、100，用来凑 15元，可以用5个2元、1个5元，或者3个5元，或者1个5元、1个10元，等等。显然，最少需要2个钱币才能凑成15元。

你的任务就是，给定若干个互不相同的钱币面值，编程计算，最少需要多少个钱币才能凑成某个给出的钱数。

-The smallest coin: This is an old and classic. Given some coins to make up a certain amount of money, in general, have a variety of ways. For example: to set a six kinds of coins the nominal value of 2,5,10,20,50,100, used to scrape together $ 15, you can use $ 5, a five yuan, or $ 3, or a yuan, a-10 yuan, and so on. Clearly, at least two coins to make up 15 yuan.

Your task is, to set a number of distinct nominal value of the coin, programming calculation, and requires a minimum number of coins to make up a given amount of money.