#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;
}