Sums
----

Using distinct single-digit numbers (other than 0), there are four ways
to create a sum of 6: 1+2+3, 1+5, 2+4, as well as 6 itself.

Your task is, given a positive integer n as input, to calculate the
number of distinct ways to create a sum of n. 

Input
-----

The input will be several non-negative integer values (each number on a
separate line) that are guaranteed to be less that 1,000,000.  The end
of the input will be indicated by a value of 0, which should not be
processed.

Output
------

For each input number, output the number of distinct ways to create a
sum equal to the input. If it is not possible to create such a sum, then
your program should output IMPOSSIBLE.

Sample Input
------------

6
23
999
0

Sample Output
-------------

4
23
IMPOSSIBLE