#include<stdio.h>
#include<string.h>
int n,i,j;
long long nr;
char *prim;
void elim(int i)
{for(int j=i;j<=n;j=j+i)
 prim[j]=0;}
int numar(int m)
{int nr=0;
 memset(prim,1,sizeof(prim));
 for(j=2;j<=m;j++)
  if(prim[j]&&m%j==0)
   elim(j);
 for(j=1;j<=n;j++)
  nr=nr+prim[j];
 return nr;}
int main()
{freopen("fractii.in","r",stdin);
 freopen("fractii.out","w",stdout);
 scanf("%d",&n);
 prim=new char[n+1];
 nr=n;
 for(i=2;i<=n;i++)
  nr=nr+numar(i);
 printf("%lld",nr);
 fclose(stdout);
 return 0;}