#include<stdio.h>
long n;

int main(void)
{
 FILE *f=fopen("fractii.in","r");
 FILE *g=fopen("fractii.out","w");
 fscanf(f,"%ld",&n);
 long nr=n;
 for(long i=2;i<=n;i++)
  {
    nr++;
    for(long j=2;j<=n;j++)
     if(i%j)
      nr++;
  }
 fprintf(g,"%ld",nr);
 fclose(g);
 return 0;
}