#include <fstream>
#include <iostream>
#include <bitset>
using namespace std;

ifstream fin ("ciur.in");
ofstream fout ("ciur.out");
int n;
bitset <2000002> sieve;
void CreateSieve ()
{
    int i, j;
    sieve[0] = sieve[1] = 1;
    for (i = 4; i <= n; i += 2)
        sieve[i] = 1;
    for (i = 3; i * i <= n; i += 2)
        if (!sieve[i])
            for (j = i * i; j <= n; j += 2 * i)
                sieve[j] = 1;
}
int main()
{
    fin >> n;
    CreateSieve();
    fout << n - sieve.count() + 1 << "\n";
    return 0;
}