刚在csdn看到了这题， 记得这是偶以前出过的一题， 现在有网站翻新了， 哈哈。
In this problem, you have to analyze a particular sorting algorithm. The algorithm processes a sequence of n distinct
 integers by swapping two adjacent sequence elements until the sequence is sorted in ascending order. For the input  
sequence 9 1 0 5 4 ,  

Ultra-QuickSort produces the output  
0 1 4 5 9 .  
Your task is to determine how many swap operations Ultra-QuickSort needs to perform in order to sort a given input sequence.  

Input
The input contains several test cases. Every test case begins with a line that contains a single integer n < 500,000 --  
the length of the input sequence. Each of the the following n lines contains a single integer 0 ≤ a[i] ≤ 999,999,999,  
the i-th input sequence element. Input is terminated by a sequence of length n = 0. This sequence must not be processed.Output
For every input sequence, your program prints a single line containing an integer number op, the minimum number of swap
 operations necessary to sort the given input sequence.
Sample Input
5
9
1
0
5
4
3
1
2
3
0
Sample Output
6
0