#include<fstream>
using namespace std;
FILE*in;
ofstream out("ciur.out");
long int N, i, j, numar, OK, v[200], p, JACK, poz;
int main()
{
	in=fopen("ciur.in","r");
	fscanf(in,"%d",&N);
	for (i=1; i<N; i++)
		v[i]=i+1;
	JACK=1;
	p=2;
	poz=1;
	while (JACK)
	{
		OK=p;
		for (i=1; i<N; i++)
			if ((v[i]%p==0) & (v[i]>p))
				v[i]=-1;
		for (j=poz+1; j<N; j++)
			if (v[j]!=-1)
			{
				p=v[j];
				break;
				poz=j;
			}
		if (p==OK)
			JACK=0;
	}
	for (i=1; i<N; i++)
		if (v[i]!=-1)
			numar++;
	out<<numar;	
	return 0;
}