#include <cstdio>
using namespace std;

FILE *f=fopen ("fractii.in","r");
FILE *g=fopen ("fractii.out","w");

int phi[1000005];

int main(){
	int n;
	long long s=0;
	
	fscanf (f,"%d",&n);
	
	for (int i=1;i<=n;++i) phi[i]=i;

	for (int i=2;i<=n;++i){
		if (phi[i]==i){
			for (int j=i;j<=n;j+=i){
				phi[j]/=i;
				phi[j]*=(i-1);
			}
		}
		s+=phi[i];
	}
	
	fprintf (g,"%lld",s*2+1);
	
	return 0;
}