#include <stdio.h>

int main(){

long int n,j,i;
freopen ("fractii.in", "r", stdin);
freopen ("fractii.out", "w", stdout);

scanf ("%ld", &n);
long int a[n];
long long s = 0;

for (j = 1; j <= n; j++)
	a[j] = j - 1;	
for (i = 2; i <=n; i ++)
	for (j = 2*i;j <= n;j +=i)
	a[j] -= a[i];
for (i = 1; i <= n; i++)
	s = s + a[i];
printf ("%lld", s*2 + 1);
return 0;
}