#include <stdlib.h>
#include <stdio.h>
int n;
long long sol;
int v[1000002];
long long ciurulluieratostene(int n)
{
    int i,j;
    for (i = 2; i <= n; i++)
    {
        v[i] = i - 1;
    }
    for (i = 2; i <= n; i++)
    {
        for (j = 2 * i; j <= n; j+=i)
        {
            v[j] -= v[i];
        }
    }
    long long total=0;
    for (i = 1; i <= n; i++)total += v[i];
    total *= 2;
    total++;
    return total;
}
int main()
{
    int i,j,curent;
    freopen("fractii.in", "r", stdin);
    freopen("fractii.out", "w", stdout);
    scanf("%d", &n);

    printf("%d",ciurulluieratostene(n));
    return 0;
}