#include<iostream>
using namespace std;

int main(){
	int yaku = 0,n,hoge = 0;
	while(cin >> n){
		hoge = 0;
		for(int i = 1;i <= n;i++){
			yaku = 0;
			for(int j = 1;j <= i;j++){
				if(i % j == 0) yaku++;
			}
			if ( yaku == 2)	hoge ++;
		}
		cout <<  hoge << endl;

	}

}