#include <fstream>

using namespace std;
ifstream fin("fractii.in");
ofstream fout("fractii.out");
const int nmax = 1000005;
int n,phi[nmax];
long long sol;
int main()
{
    int i,j;
    fin>>n;
    for(i = 2; 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];
    for(i = 2; i <= n; i++) sol+=phi[i];
    fout<<2*sol+1<<"\n";
    fout.close();
    return 0;
}