Here are two numbers A and B (0 < A <= B). If B cannot be divisible by A, and A and B are not co-prime numbers, we define A as a special number of B.
For each x, f(x) equals to the amount of x’s special numbers.
For example, f(6)=1, because 6 only have one special number which is 4. And f(12)=3, its special numbers are 8,9,10.
When f(x) is odd, we consider x as a real number.
Now given 2 integers x and y, your job is to calculate how many real numbers are between them.