#include <fstream>
#define nmax 1000002
using namespace std;
int a[nmax],n;
long long y;
ifstream f("fractii.in");
ofstream g("fractii.out");
void citire(int &n)
{
    f>>n;
}
void numere(long long &y)
{   int i,j;
    for (i=2;i<=n;i++) {a[i]+=i-1;
    for (j=2*i;j<=n;j+=i) a[j]-=a[i];
    y+=a[i];};
}
int main()
{
    citire(n);
    numere(y);
    g<<2*y+1;
    return 0;
}