#include <fstream>

using namespace std;

ifstream in("ciur.in");
ofstream out("ciur.out");

unsigned int N,x,nr,b;

int main()
{
	in>>N;
	if(N>=3)
	{
		x=3;
		nr++;
		while(x<=N)
		{
			b=1;
			if(x%2!=0)
			{
				if(x%5!=0 || x==5)
				{
					unsigned int d=2;
					b=0;
					while(d<=x/2)
					{
						if(x%d==0)
							{
								b=1;
								break;
							}
						d++;
					}
				}
			}
			if(b==0)nr++;
			x++;
		}
		out<<nr;
	}
	else out<<1;
	in.close();
	out.close();
	return 0;
}