#include <fstream>
#define ll long long
using namespace std;
ifstream f("fractii.in");
ofstream g("fractii.out");
int n,v[1000005];
int main()
{   int i,j;
    ll k = 0;
    f>>n;
    for( i = 2; i <= n; i++) v[i] = i - 1;
    for(i = 2; i <= n; i++)
        {   k += v[i];
            for(int j = i + i; j <= n; j = j + i) v[j] = v[j] - v[i];
        }
    g << 2 * k + 1; g.close(); return 0;
}