#include<stdio.h>
#include<math.h>
#define MAXSIZE 1000001

int n;

int citire()
{
FILE *f=fopen("fractii.in","r");
fscanf(f,"%d",&n);
fclose(f);
return 1;
}
int  p[MAXSIZE];
int numar(int q) {
	 int i, j, nr = 0,t;


	 if(q%2==0)
		{
		 for(i=2;i<=n;i++) {p[i]=(i%2==0&&q%2==0); }
		 for(i=3; i<=n; i+=2)
		{
		 if(p[i]==0)
			{
			 if(q%i==0||i%q==0)
				 for(j=i; j<=n; j+=i) p[j]=1;
			 else nr++;
			}
		}

		}
		else{

	 for(i=2;i<=n;i++) p[i]=0;
	 for(i=2; i<=n; i++)
		{
		 if(p[i]==0)
			{
			 if(q%i==0||i%q==0)
				 for(j=i; j<=n; j+=i) p[j]=1;
			 else nr++;
			}
		}

		}
	 return nr;
 }

int main(void)
{
int i,nr=0;
FILE *f;
citire();
nr=2*n-1;
for(i=2;i<=n;i++) nr+=numar(i);
f=fopen("fractii.out","w");
fprintf(f,"%d\n",nr);
fclose(f);
return 0;
}