5810：Balls and Boxes

Mr. Chopsticks is interested in random phenomena, and he conducts an experiment to study randomness. In the experiment, he throws n balls into m boxes in such a manner that each ball has equal probability of going to each boxes. After the experiment, he calculated the statistical variance V as
$$V=\frac{\sum_{i=1}^{m}(X_{i}-\bar X)^{2}}{m}$$
where $X_{i}$ is the number of balls in the ith box, and $\bar X$ is the average number of balls in a box.
Your task is to find out the expected value of V.

The input contains multiple test cases. Each case contains two integers n and m (1 <= n, m <= 1000 000 000) in a line.
The input is terminated by n = m = 0.

For each case, output the result as A/B in a line, where A/B should be an irreducible fraction. Let B=1 if the result is an integer.