#include <stdio.h>
#include <stdbool.h>
#include <stdlib.h>

const int maxn = 2e8 + 7;
const int cache = 20000;


int if_compound[40000];

int primes[15000];
int prime_end;

void push_prime(int x) {
    primes[prime_end] = x;
    ++prime_end;
}

int primes_size() {
    return prime_end;
}

void set_bit(int i) {
    int num = i / 32;
    int bit = i % 32;
    if_compound[num] |= 1 << bit;
}

int ask_bit(int i) {
    int num = i / 32;
    int bit = i % 32;
    return if_compound[num] == (if_compound[num] | (1 << bit));
}

void clear() {
    int i = 0;
    for (i; i < 40000; ++i)
        if_compound[i] = 0;
}

int min(int a, int b) {
    if (a < b)
        return a;
    else
        return b;
}

int main() {
    int n, i, j, lst, x;
    lst = 0;
    scanf("%d", &n);
    int ans = 0;
    for (i = 2; i * i <= n; ++i)
        if (!ask_bit(i)) {
            ++ans;
            push_prime(i);
            for (j = i; j * j <= n; j += i)
                set_bit(j);
        }
    int l = i;
    int r = min(l + cache, n + 1);
    while (l <= n) {
        clear();
        for (x = 0; x < primes_size(); ++x) {
            for (i = ((l + primes[x] - 1) / primes[x]) * primes[x]; i < r; i += primes[x]) {
                set_bit(i - l);
            }
        }
        for (i = l; i < r; ++i)
            if (!ask_bit(i - l))
                ++ans;
        l += cache;
        r = min(l + cache, n + 1);
    }
    printf("%d", ans);
    return 0;
}