|
H |
Number Transformation Input: Standard Input Output: Standard Output |
You are given an integer number S. You can transform any integer number A to another integer number B by adding x to A. This x is an integer number which is a prime factor of A (Please note that 1 and A are not being considered as a factor of A). Now, your task is to find the minimum number of transformations required to transform S to another integer number T.
Input
For each test case, there will be a line with
two integers, S (1<=S<=100) & T (1<=T<=1000),
as described above. The last test case will be followed by a line with two 0 s
denoting end of output. This case should not be processed.
Output
For every test case except the last one, print a line of the form “Case X: Y” where X is the serial number of output (starting from 1). Y is the minimum number of transformations required to transform S to T. If it is not possible to make T from S with the given rules, Y shall be -1.
|
6 12 6 13 0 0 |
Case 1: 2 Case 2: -1 |
Explanation of case 1: You can make 12 from 6 in 2 steps in this way: 6->9->12.
Problem Setter:
Mohammad Mahmudur Rahman, Special Thanks: