#include <fstream>
#include <iostream>
using namespace std;

int n;
int c=0;
int phi[1000000];
void cit()
{
    ifstream f;
    f.open("fractii.in");
    f>>n;
    f.close();
}
int cmmdc(int a,int b)
{
    if (a==0) return b;
    if (b==0) return a;
    return cmmdc(b,a%b);
}
long sum()
{
    long s=0;
    for (int i=1;i<=n;i++)
        s+=phi[i];
    return s;
}
int main()
{
    cit();
    for (int i=1;i<=n;i++)
        phi[i]=i-1;
    for (int i=1;i<=n;i++)
        for (int j=2*i;j<=n;j+=i)
            phi[j]-=phi[i];
    ofstream g;
    g.open("fractii.out");
    g<<2*sum()+1;
    g.close();
    return 0;
}