#include <bits/stdc++.h>
using namespace std;
ifstream fin("fractii.in");
ofstream fout("fractii.out");
#define int long long
const int NMAX = 1e6 + 5;
int a[NMAX];

void ciur(int n)
{
    a[0] = a[1] = 1;
    for(int i = 2; i <= n; i++)
        a[i] = i - 1;
    for(int i = 2; i <= n; i++)
        for(int j = 2 * i; j <= n; j += i)
            a[j] -= a[i];
}

signed main()
{
    int n, ans = 0;
    fin >> n;
    ciur(n);
    for(int i = 1; i <= n; i++)
        ans += 2 * a[i];
    fout << ans - 1;

    return 0;
}