#include <stdio.h>
#include <math.h>

int n;

void citire()
{
	FILE *fin;
	fin = fopen("fractii.in", "r");
	fscanf(fin, "%d", &n);
	fclose(fin);
}

int prim(int n)
{
	if(n<=1)
		return 0;
	int i;
	for(i=2;i<=sqrt(n);i++)
		if(n%i==0)
			return 0;
	return 1;
}

int prime(int n, int nr)
{
	int i, s= 1;
	for(i=2;i<=n;i++)
		if(prim(i))
			if(nr!=i)
				s++;
	return s;
}

void suma()
{
	FILE *fout;
	int s = n;
	int i;
	if(n>1)
		for(i=2;i<=n;i++)
			s += prime(n, i);
	fout = fopen("fractii.out", "w");
	fprintf(fout, "%d", s);
	fclose(fout);
}

int main()
{
	citire();
	suma();
	return 0;
}