#include <stdio.h>
#include <math.h>
int main()
{long long s=0;
 int v[10000000],i,j,n;
 
  
 freopen("fractii.in","r",stdin);
 freopen("fractii.out","w",stdout);
 scanf("%d",&n);
 
  for(i=1;i<=n;i++)  
     v[i]=i-1;  
   
 for(i=2;i<=n;i++)  
     {for(j=2*i;j<=n;j+=i)  
         v[j]-=v[i];  
     s+=v[i];}  
 
 printf("%lld",2*s+1);
  return 0;}