#include <iostream>
#include <stdio.h>

using namespace std;
const int NMAX = 1e6;

int phi[NMAX + 1];

int main()
{
    int n, i, j;
    FILE *fin = fopen("fractii.in", "r");
    fscanf(fin, "%d", &n);
    fclose(fin);

    phi[1] = 0;
    for (i = 2; i <= n; i++)
        phi[i] = i;
    for (i = 2; i <= n; i++)
        if (phi[i] == i)
            for (j = i; j <= n; j += i)
                phi[j] = phi[j] / i * (i - 1);

    int sum = 0;
    for (i = 1; i <= n; i++)
        sum += phi[i];

    FILE *fout = fopen("fractii.out", "w");
    fprintf(fout, "%d", sum * 2 + 1);
    fclose(fout);
    return 0;
}