import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;

public class Main {
	public static void main(String[] args) throws Exception {
		Scanner sc = new Scanner(System.in);
		long n = sc.nextLong();
		sc.close();

		List<Integer> list = new ArrayList<>();
		for (int i = 2; list.size() < 15; i++) {
			if (isSosuu(i)) {
				list.add(i);
			}
		}

		long v = 1;
		for (int i = 0; i < 15; i++) {
			v *= list.get(i);
			if (v > n) {
				System.out.println(i);
				return;
			}
		}
		System.out.println(15);
	}

	static boolean isSosuu(long n) {
		if (n < 2) return false;
		if (n == 2) return true;
		long end = (int) Math.sqrt(n) + 1;
		for (int i = 2; i <= end; i++) {
			if (n % i == 0) {
				return false;
			}
		}
		return true;
	}
}