#include <atcoder/all>
#include <bits/stdc++.h>
using namespace std;
using namespace atcoder;
#define rep(i, n) REP(i, 0, n)
#define REP(i, s, e) for (int i = (s); i < (int)(e); i++)
#define repr(i, n) REPR(i, n, 0)
#define REPR(i, s, e) for (int i = (int)(s - 1); i >= (int)(e); i--)
#define all(r) r.begin(), r.end()
#define rall(r) r.rbegin(), r.rend()

typedef long long ll;
typedef vector<int> vi;
typedef vector<ll> vl;

template <typename T, typename U>
T chmax(T& a, const U& b) {
    if (a >= b) return false;
    a = b;
    return true;
}
template <typename T, typename U>
T chmin(T& a, const U& b) {
    if (a <= b) return false;
    a = b;
    return true;
}

void yes_no(bool f, string yes = "Yes", string no = "No") { cout << (f ? yes : no) << "\n"; }

using Facts = map<ll, int>;
void factrize(ll n, Facts& mp) {
    if (n < 2) return;
    ll m = sqrt(n);
    REP(i, 2, m + 1) {
        int cnt = 0;
        while (n % i == 0) {
            n /= i;
            ++cnt;
        }
        if (cnt != 0) mp[i] += cnt;
    }
    if (n != 1) mp[n]++;
}

struct Sieve {
    vector<int> primes;
    vector<int> _isPrime;
    vector<int> prime_factor_num; // soinsuu no kosuu
    Sieve(int n) : _isPrime(n + 1, 1), prime_factor_num(n + 1, 0) {
        buildPrimes();
    }
    void buildPrimes() {
        _isPrime[0] = _isPrime[1] = 0;
        int n = _isPrime.size();
        REP(i, 2, n) {
            if (_isPrime[i]) {
                primes.push_back(i);
                prime_factor_num[i] = 1;
                for (int j = i + i; j < n; j += i) _isPrime[j] = 0, prime_factor_num[j]++;
            }
        }
    }
    bool isPrime(int i) {
        return _isPrime[i];
    }
};

void solve() {
    ll n;
    cin >> n;
    Sieve sieve(n + 1);
    vl a(n + 1, 1);
    for (ll i = 2; i * i <= n; ++i) {
        ll i2 = i * i;
        for (ll j = i2; j <= n; j += i2) {
            a[j] = 0;
        }
    }
    ll ans = 1;
    REP(i, 2, n + 1)
    if (a[i]) {
        ans += (sieve.prime_factor_num[i] & 1) ? -1 : 1;
    }
    cout << ans << "\n";
}

int main() {
    cin.tie(0);
    ios::sync_with_stdio(false);
    int t = 1;
    // multi-testcase
    // cin >> t;
    rep(ti, t) solve();
    return 0;
}