#include <iostream>
#include <stdio.h>
 
using namespace std;
 
int phi[1000001];
 
int main()
{
    int n;
    FILE *f = fopen("fractii.in", "r");
    fscanf(f, "%d", &n);
    fclose(f);
 
    phi[1] = 0;
    for (int i = 2; i <= n; i++)
        phi[i] = i;
    for (int i = 2; i <= n; i++)
        if (phi[i] == i)
            for (int j = i; j <= n; j += i)
                phi[j] = phi[j] / i * (i - 1);
 
    long long s = 0;
    for (int i = 1; i <= n; i++)
        s += phi[i];
 
    FILE *g = fopen("fractii.out", "w");
    fprintf(g, "%lld", s * 2 + 1);
    fclose(g);
    return 0;
}