#include <fstream>
using namespace std;

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

long long int phi[1000008];
long long int total;

int main()
{
    int N,i,j;
    fin>>N;
    for (i = 1; i <= N; ++i)
        phi[i] = i-1;
    for (i = 2; i <= N; ++i){
        for (j = 2*i; j <= N; j += i)
            phi[j] -= phi[i];
        total += phi[i-1];
    }
    total += phi[N];
    fout<<total*2+1;
}