#include <fstream>
#include <cstring>

using namespace std;

ifstream fin("ciur.in");
ofstream fout("ciur.out");

#define maxsize 2000000

char at1[maxsize / 16];
int n;

int isPrime(int x)
{
    if (!(x & 1))
        if (x == 2)
            return 0 ;
        else
            return 1 ;
    else
        return (at1[((x - 3) >> 1) >> 8] & (1 << (((x - 3) >> 1) & 7))) ;
}

void sieve()
{
    int i, j;
    memset(at1, 0, sizeof(at1)) ;
    for (i = 3; i <= n; i += 2)
        if (!at1[((i - 3) >> 1) >> 8] & (1 << (((i - 3) >> 1) & 7)))
            for (j = i * i ; j <= n ; j += i + i)
                at1[((i - 3) >> 1) >> 8] |= (1 << (((i - 3) >> 1) & 7)) ;
}


int main()
{
    int cnt = 0;
    fin >> n;
    sieve();
    for (int i = 1; i <= n; i += 2)
    {
        if (!isPrime(i))
            ++cnt;
    }
    fout << cnt << '\n';
    return 0;
}