408787: GYM103317 C Cactus Juice

Socka is venturing into the business world of the Earth Empire. He finds a vibrant market for cactus juice but he also realizes that his customers are very picky. They will only leave a tip if he serves $$$x$$$ mL of cactus juice where the number $$$x$$$ has exactly two distinct prime divisors.

So for example, Socka will get tips if he serves glasses with $$$18$$$ or $$$24$$$ mL of cactus juice but his customers won't be happy if they get $$$4$$$ or $$$8$$$ mL of cactus juice. Given that the glasses can hold any amount up to (and including) $$$n$$$ mL and the glasses cannot be empty, help Socka determine how many different sizes of cactus juice that he can serve so that he still gets a tip for every size.

The first and only line of input will contain a single integer $$$n$$$ ($$$1 \leq n \leq 5000$$$) where $$$n$$$ is the maximum mL of cactus juice that still fits in a glass.

A single integer with the number of sizes such that Socka still gets a tip for every size served.

11

2

20

7

In the first example, Socka can serve glasses with $$$6$$$ mL of cactus juice and $$$10$$$ mL of cactus juice and no other size satisfies our condition.