//#include <windows.h>
#include <stdio.h>
#include <stdlib.h>

int main(int argc, char *argv[])
{
   FILE *f = fopen("fractii.in","r");
   FILE *g = fopen("fractii.out","w+");
   long n;
   fscanf(f,"%ld",&n);
   long primes[n+1];
   long  i=1;
   long j=0;
   long long sum=0;
      for (i=2;i<=n;i++)
             primes[i]=i-1;
   for (i=2;i<=n;i++){

          for (j=2*i;j<=n;j=j+i)
              primes[j]-=primes[i];
       }
  // for (i=2;i<=n;i++)
    //   printf("%ld ",primes[i]);
   for (i=2;i<=n;i++)
       sum+=primes[i];
       
                  
   fprintf(g,"%ld",sum*2+1);
   fclose(f);
   fclose(g);
  return 0;
}