#include<stdio.h>
FILE *f=fopen("fractii.in","r"),
     *g=fopen("fractii.out","w");
long long a[1000000],i,j,n,k;
int main()
{ fscanf(f,"%lld",&n);
  for(i=1;i<=n;i++) a[i]=n;
  for(i=2;i<=n;i++){ if(a[i]==n) { for(j=i;j<=n;j+=i){  a[i]--;
                                      }

  					 for(j=i+i;j<=n;j+=i) a[j]=a[j]-(n-a[i])+1;
                                 }
                    else a[i]--;
  					k+=a[i];
                  }
  k+=n;
  fprintf(g,"%lld\n",k);
  fclose(f);
  fclose(g);
  return 0;
}