#include <iostream>
#include <fstream>
#define nmax 1000002

using namespace std;

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

long long n,phi[nmax],s;

void eul(int n){
    for (int i=2; i<=n; i++)
        phi[i]=i-1;
    for (int i=2; i<=n; i++)
        for (int j=2*i; j<=n; j+=i)
            phi[j]-=phi[i];
    for (int i=1; i<=n; i++)
        s+=phi[i];
}

int main()
{
    in >> n;
    eul(n);
    s=s*2+1;
    out << s;
    return 0;
}