#include <cstdio>
using namespace std;
int main()
{FILE*f=fopen("fractii.in","r");
FILE*g=fopen("fractii.out","w");
int s,n,i,j,nr,a[1000001]={0},k,v[1000001];
nr=0;
s=0;
fscanf(f,"%d",&n);
for(i=1; i<=n; i++)
	a[i]=i;
for(i=2; i<=n; i++)
	if(a[i]==i)
	for(j=i; j<=n; j=j+i)
		a[j]=a[j]/i*(i-1);
for(i=2; i<=n; i++)
	s=s+a[i];

fprintf(g,"%d",s*2+1);
}