#include <iostream>

using namespace std;

int main(){
	int n,count = 0;
	int result = 0;
	cin >> n;
	for (int i = 1; i <= n; i++)
	{
		count = 0;

		for (int j = 1; j <= i; j++)
		{
			if (i%j == 0)
			{
				count++;
			}
		}
		if (count == 2)
		{
			result++;
		}
	}
	cout << result << endl;
}