#include <fstream>
using namespace std;
ifstream cin("fractii.in");
ofstream cout("fractii.out");

int phi[1000100],n;
long long rs=0;
int main()
{
    cin>>n;
    for (int i=1;i<=n;i++)
        phi[i]=i-1;
    for (int i=1;i<=n;i++)
        for (int j=2;j*i<=n;j++)
          phi[i*j]-=phi[i];
    for (int i=1;i<=n;i++)
        rs+=2*phi[i];
    rs++;
    cout<<rs;
    return 0;
}