#include <stdio.h>   
FILE *f=fopen("fractii.in","r"),*g=fopen("fractii.out","w");   
long a[1000000],n,i,j,x,s;
  
int main()   
{   
      fscanf(f,"%ld",&n);   
      for(i=2;i*i<=n;++i)
     for(j=2;i*j<=n;++j)
	a[j*i]=1;
      for(i=n;i>=2;--i)
     {
     x=i;
     if(a[x]==0)
	x=x-1;
     else
     for(j=2;j<=x;++j)
	if(x%j==0 && a[j]!=1)
        x-=x/j;   
     s+=x*2;   
     }   
      s+=1;   
      fprintf(g,"%ld",s);   
      fclose(g);   
      return 0;   
}