Problem Description

Given an integer $n$, find the value of $\pi(n)$.

$\pi(n)$ denotes the number of prime numbers among the integers from $1$ to $n$.

Input Format

One line with one integer $n$.

Output Format

One line with one integer, representing the required value.

10

4

Hint

For $100\%$ of the testdata, $1 \leq n \leq 10^{13}$.

Translated by ChatGPT 5