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

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

long long cate_prime[1000001];

int n;

void setare()
{
    cate_prime[1] = 1;
    for(int i = 2; i <= n; ++i)
        cate_prime[i] = i - 1;
    for(int i = 2; i <= n; ++i)
        for(int j = i + i; j <= n; j += i)
            cate_prime[j] -= cate_prime[i];
}

int main()
{
    fin >> n;

    setare();

    long long s = 0;
    for(int i = 2; i <= n; ++i)
        s += cate_prime[i];
    fout << s * 2 + 1;
    return 0;
}