Find the Count of Numbers Which Are Not Special - Solution & Explanation

You are given 2 positive integers l and r. For any number x, all positive divisors of x except x are called the proper divisors of x.

A number is called special if it has exactly 2 proper divisors. For example:

• The number 4 is special because it has proper divisors 1 and 2.
• The number 6 is not special because it has proper divisors 1, 2, and 3.

Return the count of numbers in the range [l, r] that are not special.

 

Example 1:

Example 2:

 

Constraints:

• 1 <= l <= r <= 109