1. #include <stdio.h>  
   2.   
   3. long long n,i,j,a[1000002];  
   4. int main()  
   5. {  
   6.     freopen("fractii.in","r",stdin);  
   7.     freopen("fractii.out","w",stdout);  
   8.     scanf("%lld",&n);  
   9.     for (i=1; i<=n; ++i) a[i]=i-1;  
  10.     for (i=2; i<=n; ++i)  
  11.         for (j=i*2; j<=n; j+=i) a[j]-=a[i];  
  12.     for (i=0, j=0; i<=n; ++i, j+=a[i]);  
  13.     printf("%lld",j*2+1);  
  14.     return 0;  
  15. }