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

int main(void)
{
	int i,j,n,k,v[1000001],t;
	FILE *f,*g;
	f=fopen("fractii.in","r");
	g=fopen("fractii.out","w");
	k=0;
	fscanf(f,"%d",&n);
	for(i=2;i<=n;i++) v[i]=i-1;
	for(i=2;i<=n;i++)
	{
		k=k+v[i];
		for(j=2*i;j<=n;j+=i) v[j] = v[i] - v[i];
	}
	fprintf(g,"%d\n",2*k+1);
	fclose(f);
	fclose(g);
	return 0;
}