Divisor Increase#11487
There is an integer . You are allowed to add to any of its divisors not equal to and . The same operation can be applied to the resulting number and so on. Notice that starting from the number , we can reach any composite number by applying several such operations. For example, the number can be reached starting from using operations: 4 \rightarrow 6 \rightarrow 8 \rightarrow 12 \rightarrow 18 \rightarrow 24.
Find the minimal number of operations necessary to transform into .
Each line contains two integers and m\:(4 \le n \le m \le 10^5).
For each test case, print in a separate line the minimal number of operations to transform into . Print if can't be obtained from .
Example 1