#include<fstream>
using namespace std;
long long n,k=0,c[100001],i,j;
int main() 
{ 
     ifstream f("fractii.in"); 
     ofstream g("fractii.out"); 
	 f>>n; 
     f.close();
     for(i=2;i<=n;i++) 
     c[i]=i-1; 
    for(i=2;i<=n;i++) 
{ 
    k=k+c[i]; 
    for(j=i*2;j<=n;j=j+i) 
    c[j]=c[j]-c[i]; 
} 
    if(k=k*2+1)
    g<<k<<" "; 
    g.close();
    return 0;
 }