#include <fstream.h>   
#define MaxN 1000009   

int i,j,n,v[MaxN];   
long long nr;   
  
int main()   
{   
    ifstream fin("fractii.in");   
    fin>>n;   
    fin.close();   
    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];      
    }      
       
    nr*=2;    
    nr++;   
    ofstream fout("fractii.out");   
    fout<<nr;   
    fout.close();   
    return 0;   
}