#include <fstream>
#include <bitset>
#include <vector>
#define nmax 2000000
using namespace std;

ifstream cin("ciur.in");
ofstream cout("ciur.out");

bitset <nmax + 1> seive;
vector <int> primeNumbers;

void ciur(int limit){
    seive[0] = seive[1] = true;
    for(int i = 4; i <= limit; i += 2){
        seive[i] = true;
    }
    for(int i = 3; i * i <= limit; i += 2){
        if(!seive[i]){
            for(int j = i * i; j <= limit; j += 2 * i){
                seive[j] = true;
            }
        }
    }
    for(int i = 1; i <= limit; ++i){
        if(!seive[i]){
            primeNumbers.push_back(i);
        }
    }
}

bool primeFactors(int number){
    int divisor = 0;
    while(number > 1){
        int pow = 0;
        while(number % primeNumbers[divisor] == 0){
            number /= primeNumbers[divisor];
            pow++;
        }
        if(pow){
            return false;
        }
        divisor++;
        if(primeNumbers[divisor] * primeNumbers[divisor] > number){
            return true;
        }
    }
    return true;
}

int main(){
    int limit, countPrimeNumbers = 0;
    cin >> limit;
    ciur(limit);
    for(int i = 1; i <= limit; i += 2){
        if(primeFactors(i)){
            countPrimeNumbers++;
        }
        if(i == 2){
            countPrimeNumbers++;
        }
    }
    cout << countPrimeNumbers;
    return 0;
}