fn main() {
    input!{
		n: usize,
	}

	// 10^3ぐらいまで、素数を求める
	let eratos = erato(1_000);
	fn erato(x: usize) -> Vec<usize> {
		let mut ret = Vec::new();
		let mut used = vec![true; x+1];
		used[0] = false; used[1] = false;

		for i in 2..=x {
			if !used[i] { continue; }
			let mut multi = 2;
			ret.push(i);
			while i * multi <= x {
				used[i * multi] = false;
				multi += 1;
			}
		}

		ret
	}

	let mut now = 1u128;
	let mut cnt = 0;
	while now * eratos[cnt] as u128 <= n as u128{
		now *= eratos[cnt] as u128;
		cnt += 1;
	}
	println!("{}", cnt);
}
// ---------- begin input macro ----------
#[macro_export]
macro_rules! input {
    (source = $s:expr, $($r:tt)*) => {
        let mut iter = $s.split_whitespace();
        input_inner!{iter, $($r)*}
    };
    ($($r:tt)*) => {
        let s = {
            use std::io::Read;
            let mut s = String::new();
            std::io::stdin().read_to_string(&mut s).unwrap();
            s
        };
        let mut iter = s.split_whitespace();
        input_inner!{iter, $($r)*}
    };
}

#[macro_export]
macro_rules! input_inner {
    ($iter:expr) => {};
    ($iter:expr, ) => {};
    ($iter:expr, $var:ident : $t:tt $($r:tt)*) => {
        let $var = read_value!($iter, $t);
        input_inner!{$iter $($r)*}
    };
}

#[macro_export]
macro_rules! read_value {
    ($iter:expr, ( $($t:tt),* )) => {
        ( $(read_value!($iter, $t)),* )
    };
    ($iter:expr, [ $t:tt ; $len:expr ]) => {
        (0..$len).map(|_| read_value!($iter, $t)).collect::<Vec<_>>()
    };
    ($iter:expr, chars) => {
        read_value!($iter, String).chars().collect::<Vec<char>>()
    };
    ($iter:expr, bytes) => {
        read_value!($iter, String).bytes().collect::<Vec<u8>>()
    };
    ($iter:expr, usize1) => {
        read_value!($iter, usize) - 1
    };
    ($iter:expr, $t:ty) => {
        $iter.next().unwrap().parse::<$t>().expect("Parse error")
    };
}
// ---------- end input macro ----------
#[allow(unused)]
use std::{
	io::stderr, io::stdin, io::BufRead, io::Write,
	mem::swap,
	cmp::min, cmp::max,
	cmp::Reverse,
	collections::HashSet, collections::BTreeSet,
	collections::HashMap, collections::BTreeMap,
	collections::BinaryHeap,
	collections::VecDeque,
};