#include <bits/stdc++.h>

#include <atcoder/all>
using namespace std;
using i32 = int;
using u32 = unsigned int;
using i64 = long long;
using u64 = unsigned long long;
#define FAST_IO                \
  ios::sync_with_stdio(false); \
  cin.tie(0);
const i64 INF = 1001001001001001001;
using Modint = atcoder::static_modint<998244353>;

int main() {
  FAST_IO

  int N;
  cin >> N;

  vector<int> a(N + 1, 1);
  a[0] = 0;
  vector<bool> is_prime(N + 1, true);
  for (int i = 2; i <= N; i ++) {
    if (is_prime[i]) {
      if (1LL * i * i <= N) {
        for (int j = i * i; j <= N; j += i * i) {
          a[j] = 0;
        }
      }
      for (int j = i; j <= N; j += i) {
        is_prime[j] = false;
        a[j] *= -1;
      }
    }
  }
  int ans = 0;
  for (auto v : a) {
    ans += v;
  }
  cout << ans << endl;
}