E. Multiplications
---------------
In this problem, you have to find the number of different ways that you can 
fill in distinct digits between 1 and 9 (inclusive) for stars in a 
multiplication formula like
** x ** = ***.
For example, you could fill in this formula with 18 x 42 = 756 or
67 x 14 = 938.  Note that you cannot use the same digit twice, 
so 56 x 14 = 784 is not a legal solution (it uses the digit 4 twice).
67 x 14 = 938 and 14 x 67 = 938 count as two different ways of filling
in the formula.

Input Format
------------
The input will consist of multiple instances.

For each instance, there will one line containing 3 positive integers
n, m and p, separated by single spaces.  The three integers give
the number of digits in the first factor, the second
factor and the product.  (For example, the formula *** x ** = ****
would be described by an input line with n=3, m=2, p=4.)  You may assume
that n+m+p <= 9.

The end of the input will be indicated by a line with n=m=p=0.  Do
not produce any output for this input line.

Output Format
-------------
For each input instance, output a single integer on a separate line.
That integer should be the number of different ways to fill in the 
multiplication using distinct digits between 1 and 9.

Sample Input
------------
1 1 1
1 1 2
0 0 0

Sample Output
-------------
4
32