#include <fstream>

using namespace std;
ifstream fin("fractii.in");
ofstream fout("fractii.out");
int n;
unsigned long long nr=0;
int a[1000001];
void citire()
{
    fin>>n;
}

int main()
{
    int i,j;
    citire();
    for(i=1;i<=n;i++)
        a[i]=i-1;
    for(i=2;i<=n;i++)
        {for(j=2*i;j<=n;j=j+i)
            a[j]=a[j]-a[i];
        nr=nr+2*a[i];
        }
    nr++;
    fout<<nr;


    return 0;
}