P17281 "IXOI R2" Kexue Expert I

> Obito and Rin are a great ship.

Rin has $n$ integers $1 \sim n$. Obito can now choose at least $2$ numbers and obtain their greatest common divisor. After each choice, the numbers are not removed, and the next time he can choose repeatedly. Obito can make any number of choices. Ask how many different numbers he can obtain.

One line with one integer $n$.

One line, output the answer.

### Sample Explanation Sample #1: The greatest common divisors are $\gcd(1,2)=1,\gcd(1,3)=1,\gcd(2,3)=1,\gcd(1,2,3)=1$, so there is one in total. Sample #2: It can be obtained that there are two different greatest common divisors in total. ### Constraints **This problem uses bundled testdata.** |Subtask|$n\le$|Score| |:-:|:-:|:-:| |$1$|$4000$|$20$| |$2$|$10^6$|$30$| |$3$|$10^{18}$|$50$| For all data, it is guaranteed that: $1\le n \le 10^{18}$。 Translated by ChatGPT 5