#include<stdio.h>
FILE*fin=fopen("fractii.in","r");
FILE*fout=fopen("fractii.out","w");
#define nm 1000005
int p[nm],n;
int main()
{
  long long ans=0;  
  int i,j;
  fscanf(fin,"%d",&n);
  for(i=2;i<=n;i++)
    p[i]=i-1;
  for(i=2;i<=n;i++)
  {
    for(j=2*i;j<=n;j+=i)
      p[j]-=p[i];
    ans+=p[i];
  }    
  fprintf(fout,"%lld",2*ans+1);
  fclose(fin);
  fclose(fout);
  return 0;
}