#include <cstdio>

using namespace std;

const int maxn = 1000005;
long long n, sol[maxn], sum;

int main()
{
    int i, j;
    freopen ("fractii.in", "r", stdin);
    freopen ("fractii.out", "w", stdout);
    scanf("%lld", &n);
    for (i = 1; i <= n; ++i)
        sol[i] = i-1;
    for (i = 2; i <= n; ++i) {
        sum += sol[i];
        for (j = 2 * i; j <= n; j += i)
            sol[j] -= sol[i];
    }
    printf("%lld", 2 * sum + 1);
    return 0;
}