There are $n$ black balls and $m$ white balls in the big box.
Now, DZY starts to randomly pick out the balls one by one. It forms a sequence $S$. If at the $i$-th operation, DZY takes out the black ball, $S_i=1$, otherwise $S_i=0$.
DZY wants to know the expected times that '01' occurs in $S$.
The input consists several test cases. ($TestCase\leq 150$)
The first line contains two integers, $n$, $m(1\leq n,m\leq 12)$
For each case, output the corresponding result, the format is $p/q$($p$ and $q$ are coprime)