Self-describing Sequence

时间： 1ms 内存：64M

描述：

Self-describing Sequence

Solomon Golomb's self-describing sequence {f (1), f (2), f (3),...} is the only non-decreasing sequence of positive integers with the property that it contains exactly f (k) occurrences of k for each k. A few moment's thought reveals that the sequence must begin as follows:

n 1 2 3 4 5 6 7 8 9 10 11 12
f (n) 1 2 2 3 3 4 4 4 5 5 5 6

In this problem you are expected to write a program that calculates the value of f (n) given the value of n.

输入：

The input may contain multiple test cases. Each test case occupies a separate line and contains an integer n ( 1<=n<=2, 000, 000, 000). The input terminates with a test case containing a value 0 for n and this case must not be processed.

输出：