#include <fstream>
#include <bitset>
#include <iostream>
#define NMAX 150000
#define NNMAX 2000000

using namespace std;

ifstream f("ciur.in");
ofstream g("ciur.out");

int n, cont=0;
bitset <NNMAX+4> v;

void ciur()
{
    int i, j;
    v[0]=v[1]=1;

    for (i=4; i<=NNMAX; i+=2) v[i]=1;

    for (i=3; i<=NNMAX; i+=2)
    if (v[i]==0)
    for (j=i+i; j<=NNMAX; j+=i)
    v[j]=1;
}

int main()
{
    f>>n;
    ciur();
    //for (int i=1; i<=50; ++i) g<<v[i]<<" ";
  //  cout << n;
    for (int i=2; i<=10; ++i)
    if (v[i]==0) cont++;
    g<<cont<<'\n';
    return 0;
}