#include <fstream>
using namespace std;

ifstream fin("fractii.in");
ofstream fout("fractii.out");

long int v[100000000];

int main()
{
    long long k = 0;
    int n, i, j;
    fin >> 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];
    }
    fout << 2 * k + 1;
    return 0;
}