#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;  
   }