#include<bits/stdc++.h>
using namespace std;

int f[1000005];

int main() {
	freopen("fractii.in","r",stdin);
	freopen("fractii.out","w",stdout);
    int n;
    long long ans = 0;
    scanf("%d", &n);

    for (int i = 1; i <= n; i++) {
        f[i] = i - 1; }
    f[1] = 1;

    for (int i = 2; i <= n; i++) {
        for (int j = 2 * i; j <= n; j = j + i) {
            f[j] = f[j] - f[i]; } }

    for (int i = 2; i <= n; i++) {
        ans = ans + 2 * f[i]; }
    ans = ans + f[1];

    printf("%d", ans);
    return 0; }