#include<iostream>

using namespace std;

int main(void)
{
	int n;
	while(cin >> n){
		int sosu = 0;
		for(int i = 2; i <= n; i++){
			int count = 0;
			if(i % 2){
				for(int j = 1; j <= i; j++){
					if(i % j == 0) {
						count++;
					}
				}
				if(count == 2) sosu++;
			}
		}cout << sosu+1 << endl;
	}
	return 0;
}