#include <stdio.h>
int a[1000001];
int main(int argc, char** argv) 
{  
  freopen("fractii.in", "r", stdin);
   long n;
   long long nr=0;
   int i,j;
   scanf("%ld", &n); fclose(stdin);
    for (i=2; i<=n; ++i)  {  
                           a[i]=i-1-a[i];  
                           for (j=2; i*j <= n; ++j) a[i*j]+=a[i];  
                           nr+=a[i];  
                           }  
   freopen("fractii.out", "w", stdout);
   printf("%lld", 2*nr+1); fclose(stdout);
   return 0;
}