// ---------- begin miller-rabin ----------
fn is_prime_miller(n: u64) -> bool {
    if n <= 1 {
        return false;
    } else if n <= 3 {
        return true;
    } else if n % 2 == 0 {
        return false;
    }
    let pow = |r: u64, mut m: u64| -> u64 {
        let mut t = 1u128;
        let mut s = (r % n) as u128;
        let n = n as u128;
        while m > 0 {
            if m & 1 == 1 {
                t = t * s % n;
            }
            s = s * s % n;
            m >>= 1;
        }
        t as u64
    };
    let mut d = n - 1;
    let mut s = 0;
    while d % 2 == 0 {
        d /= 2;
        s += 1;
    }
    const B: [u64; 7] = [2, 325, 9375, 28178, 450775, 9780504, 1795265022];
    for &b in B.iter() {
        let mut a = pow(b, d);
        if a <= 1 {
            continue;
        }
        let mut i = 0;
        while i < s && a != n - 1 {
            i += 1;
            a = (a as u128 * a as u128 % n as u128) as u64;
        }
        if i >= s {
            return false;
        }
    }
    true
}
// ---------- end miller-rabin ----------
// 初期化配列
// 初期値とサイズを与えて適当にやる系
// new(size, zero): zero埋めした長さsizeの配列を返す
// init(&mut self): 初期化
// index(mut) でアクセスしたときその履歴を溜め込む
// それ以外でアクセスすると死ぬので注意
//
// 考えるべきこと
// 1. deref で dataへアクセスできるようにしていいか
//    derefmut はダメ
// 2. 今のままだと二次元配列の初期化とかには対応できない
//    なんか方法を考えたい
// ---------- begin init array ----------
#[derive(Clone)]
pub struct InitArray<T> {
    data: Vec<T>,
    used: Vec<bool>,
    list: Vec<u32>,
    zero: T,
}

impl<T: Copy> InitArray<T> {
    pub fn new(zero: T, size: usize) -> Self {
        InitArray {
            data: vec![zero; size],
            used: vec![false; size],
            list: vec![],
            zero: zero,
        }
    }
    pub fn init(&mut self) {
        self.init_with(|_, _| ());
    }
    pub fn init_with<F>(&mut self, mut f: F)
    where
        F: FnMut(usize, T),
    {
        for x in self.list.drain(..) {
            let x = x as usize;
            self.used[x] = false;
            let v = std::mem::replace(&mut self.data[x], self.zero);
            f(x, v);
        }
    }
}

impl<T> std::ops::Index<usize> for InitArray<T> {
    type Output = T;
    fn index(&self, pos: usize) -> &Self::Output {
        &self.data[pos]
    }
}

impl<T> std::ops::IndexMut<usize> for InitArray<T> {
    fn index_mut(&mut self, pos: usize) -> &mut Self::Output {
        if !self.used[pos] {
            self.used[pos] = true;
            self.list.push(pos as u32);
        }
        &mut self.data[pos]
    }
}
// ---------- end init array ----------
// ---------- begin prime count ----------
// 処理が終わった時
// large[i]: pi(floor(n / i))
// small[i]: pi(i)
// となっている
// O(N^(3/4)/log N)
pub fn prime_count(n: usize) -> (Vec<usize>, Vec<usize>) {
    if n <= 1 {
        return (vec![0, 0], vec![0, 0]);
    }
    let sqrt = (1..).find(|p| p * p > n).unwrap() - 1;
    let mut large = vec![0; sqrt + 1];
    let mut small = vec![0; sqrt + 1];
    for (i, (large, small)) in large.iter_mut().zip(&mut small).enumerate().skip(1) {
        *large = n / i - 1;
        *small = i - 1;
    }
    for p in 2..=sqrt {
        if small[p] == small[p - 1] {
            continue;
        }
        let pi = small[p] - 1;
        let q = p * p;
        for i in 1..=sqrt.min(n / q) {
            large[i] -= *large.get(i * p).unwrap_or_else(|| &small[n / (i * p)]) - pi;
        }
        for i in (q..=sqrt).rev() {
            small[i] -= small[i / p] - pi;
        }
    }
    (small, large)
}
// ---------- end prime count ----------
// ---------- begin enumerate prime ----------
fn enumerate_prime<F>(n: usize, mut f: F)
where
    F: FnMut(usize),
{
    assert!(1 <= n && n <= 5 * 10usize.pow(8));
    let batch = (n as f64).sqrt().ceil() as usize;
    let mut is_prime = vec![true; batch + 1];
    for i in (2..).take_while(|p| p * p <= batch) {
        if is_prime[i] {
            let mut j = i * i;
            while let Some(p) = is_prime.get_mut(j) {
                *p = false;
                j += i;
            }
        }
    }
    let mut prime = vec![];
    for (i, p) in is_prime.iter().enumerate().skip(2) {
        if *p && i <= n {
            f(i);
            prime.push(i);
        }
    }
    let mut l = batch + 1;
    while l <= n {
        let r = std::cmp::min(l + batch, n + 1);
        is_prime.clear();
        is_prime.resize(r - l, true);
        for &p in prime.iter() {
            let mut j = (l + p - 1) / p * p - l;
            while let Some(is_prime) = is_prime.get_mut(j) {
                *is_prime = false;
                j += p;
            }
        }
        for (i, _) in is_prime.iter().enumerate().filter(|p| *p.1) {
            f(i + l);
        }
        l += batch;
    }
}
// ---------- end enumerate prime ----------

fn read() -> usize {
    let mut s = String::new();
    std::io::stdin().read_line(&mut s).unwrap();
    s.trim().parse().unwrap()
}

fn solve(n: usize) {
    let sqrt = (2..).find(|p| p * p > n).unwrap() - 1;
    let mut pi = prime_count(n);
    for i in 1..=sqrt {
        if is_prime_miller(i as u64 + 1) {
            pi.0[i] += 1;
        }
        if is_prime_miller((n / i) as u64 + 1) {
            pi.1[i] += 1;
        }
    }
    let pi = |x: usize| -> usize {
        let x = x - 1;
        if x < pi.0.len() {
            pi.0[x]
        } else {
            pi.1[n / x]
        }
    };
    let mut prime = vec![];
    enumerate_prime(sqrt + 100000, |p| prime.push(p));
    let mut large = InitArray::new(0, sqrt + 1);
    let mut small = InitArray::new(0, sqrt + 1);
    let mut next_large = InitArray::new(0, sqrt + 1);
    let mut next_small = InitArray::new(0, sqrt + 1);
    large[1] = 1usize;
    let mut ans = 0;
    for (i, &p) in prime.iter().enumerate() {
        let mut prun = |m: usize, v: usize| -> bool {
            (p - 1) * p > m && {
                ans += v;
                if p <= m + 1 {
                    ans += v * (pi(m + 1) - i);
                }
                true
            }
        };
        large.init_with(|d, v| {
            let m = n / d;
            if prun(m, v) {
                return;
            }
            next_large[d] += v;
            let mut d = d * (p - 1);
            while d <= sqrt {
                next_large[d] += v;
                d *= p;
            }
            let mut m = n / d;
            while m > 0 {
                next_small[m] += v;
                m /= p;
            }
        });
        small.init_with(|m, v| {
            if prun(m, v) {
                return;
            }
            next_small[m] += v;
            let mut m = m / (p - 1);
            while m > 0 {
                next_small[m] += v;
                m /= p;
            }
        });
        std::mem::swap(&mut small, &mut next_small);
        std::mem::swap(&mut large, &mut next_large);
    }
    println!("{}", ans);
}

fn main() {
    solve(read());
}