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