#include<stdio.h>
int tot(int n)
	{
	long k,s=1,r;
	k=2; s=n;
	while(n!=1)
	{r=0;
	while(n%k==0) {n=n/k;r++;}
	if(r!=0) s=s*(1-1/k);
	k++;}
	return s;}

int main()
{long n,i,j,k,sol=0,x,ok,r,v[100];
FILE*f=fopen("fractii.in","r");
FILE*g=fopen("fractii.out","w");
fscanf(f,"%ld",&n);
sol=n;
for (i=2;i<=n;i++) sol+=tot(i);
fprintf(g,"%ld",sol-1);
fclose(f);
fclose(g);
return 0;}