1. #include <stdio.h>  
   2. #include <math.h>  
   3. int main()  
   4. {long long s=0;  
   5.  int v[1000001],i,j,n;  
   6.    
   7.     
   8.  freopen("fractii.in","r",stdin);  
   9.  freopen("fractii.out","w",stdout);  
  10.  scanf("%d",&n);  
  11.    
  12.   for(i=1;i<=n;i++)    
  13.      v[i]=i-1;    
  14.      
  15.  for(i=2;i<=n;i++)    
  16.      {for(j=2*i;j<=n;j+=i)    
  17.          v[j]-=v[i];    
  18.      s+=v[i];}    
  19.    
  20.  printf("%lld",2*s+1);  
  21.   return 0;}