#include <bits/stdc++.h>

using namespace std;

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

    int prime[1000001], n;
    long long sol = 0;

int main()
{
    fin >> n;
    for(int i = 1; i <= n; i++)
        prime[i] = i-1;

    for(int i = 1; i <= n; i++)
    {
        for(int j = 2 * i; j <= n; j += i)
            prime[j] -= prime[i];
        sol += prime[i];
    }
    fout << 1+2*sol;
    return 0;
}