#include <bits/stdc++.h>

using namespace std;

int phi[1000000];

int main()
{
    long long n, s;

    ifstream fin("fractii.in");
    fin>>n;
    fin.close();

    for (int i = 1; i <= 1000000; ++i)
        phi[i] = i-1;
    for (int i = 2; i <= 1000000; ++i)
        for (int j = 2*i; j <= 1000000; j += i)
            phi[j] -= phi[i];
    s = 0;
    for(int i = 1; i <= n; i++)
        s += phi[i];

    ofstream fout("fractii.out");
    fout << s * 2 + 1;
    fout.close();
    return 0;
}