Time Limit: 2 second(s) | Memory Limit: 32 MB |
In this problem, 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 starts with an integer T (≤ 500), denoting the number of test cases.
Each case contains two integers: s (1 ≤ s ≤ 100) and t (1 ≤ t ≤ 1000).
For each case, print the case number and the minimum number of transformations needed. If it's impossible, then print -1.
Sample Input |
Output for Sample Input |
2 6 12 6 13 |
Case 1: 2 Case 2: -1 |
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