#include<iostream>
#include<cstring>
using namespace std;

int isPrime[1001];

bool func(int num){
    for (int i = 2; i < num; i++){
        if (num%i == 0) isPrime[num] = 0;
    }
    if (isPrime[num] == -1) {
        isPrime[num] = 1;
        return true;
    }
    for (int i = 2; i < num; i++){
        if (isPrime[i] == 1){
            int buf = i;
            while (buf <= num){
                if (buf == num) return true;
                buf *= i;
            }
        }
    }
    return false;
}

int main(){
    int n;
    cin >> n;
    int res = 0;
    memset(isPrime, -1, 1001);
    for (int i = 2; i <= n; i++){
        if (func(i)) res++;
    }
    cout << res;
    return 0;
}