#include <stdio.h>
#include <stdlib.h>

typedef struct Nod 
{
	int value;
	struct Nod* next;
} List;

void insert(List** p, int x)
{
	List* nou = (List*) malloc(sizeof(List));
	nou->value = x;
	nou->next = NULL;

	if (*p == NULL)
	{ 
		*p = nou;
		return;
	}

	List* q;
	for(q = *p; q->next != NULL; q = q->next);
	q->next = nou;
}

void delete(List** p, int x)
{
	// primul element(2) nu va fi niciodata eliminat deoarece este prim
	List* q, * del;
	for (q = *p; q->next->value != x; q = q->next);
	del = q->next;
	q->next =  q->next->next;
	del->next = NULL;
	free(del);
}

int eratostene(List** p)
{
	List* par, * q;
	int k = 0;
	par = *p;
	while (par != NULL)
	{
		k++;
		for (q = par; q->next != NULL; )
			if (q->next->value % par->value == 0)
			{
				delete(p, q->next->value);
			}
			else q = q->next;
		
		par = par->next;
	}
	return k;
}

int main()
{
	int n, i;
	FILE * in, * out;
	in = fopen("ciur.in", "rt");
	fscanf(in, "%d", &n);
	fclose(in);

	List* p = NULL;
	for (i = 2; i <= n; i++)
		insert(&p, i);
	
	out = fopen("ciur.out", "wt");
	fprintf(out, "%d", eratostene(&p));
	return 0;
}