#include<stdio.h>
long n,k;
int main()
{
	long i;
	freopen("ciur.in","r",stdin);
	freopen("ciur.out","w",stdout);
	scanf("%ld",&n);
	if(n==2){
		printf("1\n");
		return 0;
	}
	if(n==3){
		printf("2\n");
		return 0;
	}
	for(i=4;i<=n;i++){
		if(i%2==0 || i%3==0)
			continue;
		else
			++k;
	}
	printf("%ld\n",k);
	return 0;
}