#include <stdio.h>
FILE *f,*g;
long x,i,n,v[1000001];
int main(){
 f=fopen("fractii.in","r");
 g=fopen("fractii.out","w");
 fscanf(f,"%ld",&n);
 for (i=1;i<=n;i++) v[i]=i-1;
 long long s=0;
 for (i=2;i<=n;i++){
  x=i*2;
  while (x<=n){
   v[x]=v[x]-v[i];
   x=x+i;
  }
  s+=v[i];
 }
 s=s*2+1;
 fprintf(g,"%lld",s);
 fclose(f);
 fclose(g);
 return 0;
}