## Problem A: Dice throwing

*n* common cubic dice are thrown,
1 <= *n* <= 24. What is the
probability that the sum of all thrown dice is at least *x*?

Your program should read input from file named `dice.dat`. The
file consists of a sequence of lines. Each line contains two
nonnegative integer numbers *n* and *x* separated by
white space.

For each line of input produce one line of output giving the requested
probability as a proper fraction in lowest terms in the format shown
in the sample output. All numbers appearing in output are
representable in unsigned 64-bit integers. The last line of input
contains two zeros and it should not be processed.

### Sample input

3 9
1 7
24 24
15 76
24 56
24 143
23 81
7 38
0 0

### Output for sample input

20/27
0
1
11703055/78364164096
789532654692658645/789730223053602816
25/4738381338321616896
1/2
55/46656

*P. Rudnicki*