#include<fstream>
using namespace std;

#define dim 1000002
int n;
long long sol=0;
int v[dim];
int main (){
     ifstream fin("fractii.in");
    ofstream fout("fractii.out");
    fin>>n;
    for(int i=2;i<=n;++i)
    v[i]=i-1;
    for(int i=2;i<=n;++i)
    for(int j=2;j*i<=n;++j)
        v[i*j]-=v[i];
    for(int i=2;i<=n;++i)
        sol=sol+v[i];
        sol=2*sol+1;
    fout<<sol;
     fin.close();
    fout.close();
}