#include <iostream>
#include <cmath>
#define MAX 100001
using namespace std;

int p[MAX];

int main(){
	int counter = 0;
	p[1] = 0;
	for (int i = 2; i < MAX; i++){
		int sqrti = (int)sqrt(i);
		counter++;
		p[i] = counter;
		for (int j = 2; j <= sqrti; j++){
			if (i % j == 0){
				counter--;
				p[i] = counter;
				break;
			}
		}
	}
	int n;
	while (cin >> n){
		cout << p[n] << endl;
	}
	return 0;
}