#include <bits/stdc++.h>

using namespace std;

ifstream fin ("fractii.in");
ofstream fout ("fractii.out");

const int nmax=1e6;
int n, phi[nmax];

void eratostene ()
{
    phi[0]=phi[1]=1;
    for (int i=2; i<=nmax; i++)
        phi[i]=i-1;
    for (int i=2; i<=nmax; i++)
    {
        for (int j=2*i; j<=nmax; j+=i)
            phi[j]-=phi[i];
    }
}

int main()
{
    fin >> n;
    eratostene();
    int rez=0;
    for (int i=1; i<=n; i++)
        rez+=phi[i];
    fout << rez*2-1;
    return 0;
}