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