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

int main()     
{     
FILE *in,*out;   
int i,j,n,nr=0,v[1000001];
in=fopen("fractii.in","r");     
out=fopen("fractii.out","w");     
fscanf(in,"%d",&n); 
//v=(int*)malloc(n*sizeof(int));
for(i=1;i<=n;i++)    
     v[i]=i-1;    
      
for(i=2;i<=n;i++)    
	{
	for(j=2*i;j<=n;j+=i)    
          v[j]-=v[i];    
      nr+=v[i];
	}    
fprintf(out,"%d",2*nr+1);
          
fclose(in);
fclose(out);     
return 0;
}