#include <fstream>
#define NMAX 1000005
using namespace std;

ifstream cin("fractii.in");
ofstream cout("fractii.out");

int v[NMAX];

int main()
{
    long long k = 0;
    int n, i, j;
    cin >> n;
    for(i = 2; i <= n; i++) {
        v[i] = i - 1;
    }
    for(i = 2; i <= n; i++) {
        for(j = i + i; j <= n; j = j + i) {
            v[j] = v[j] - v[i];
            }
        k += v[i];
    }
    cout << 2 * k + 1;
    return 0;
}