You have a bag filled with N balls. Each ball has a distinct number from 1 to N printed on it. All the numbers are distinct. You withdraw two balls from the bag and take their sum. You need to calculate the probability that the sum is not greater than the given number K (<= N). The answer should be displayed in the form of p/q (except when the answer is 0 or 1.)

Input

Input consists of various test cases. Each test case consist of two integer inputs, N and K. (0 <= K <= N <= 1000000000) The program stops taking input when N and K equals -1.

Output

Output the result in the form of p/q (except when the answer is 0 or 1.)

Example

Input:
3 2
100 5
10 6
-1 -1

Output:
0
2/2475
2/15