# include <fstream>
# define DIM 1000010
using namespace std;
ifstream fin("fractii.in");
ofstream fout("fractii.out");
long long s,f[DIM],n,j,i;
int main () {
    fin>>n;
    for(i=1;i<=n;i++)
        f[i]=i;
    for(i=2;i<=n;i++){
        if(f[i]==i){
            for(j=i;j<=n;j+=i){
                f[j]*=(i-1);
                f[j]/=i;
            }
        }
        s+=f[i];
    }
    fout<<2*s+1<<"\n";
    return 0;
}