#include <fstream>

using namespace std;

ifstream f("fractii.in");
ofstream g("fractii.out");

long long N,result;
int phi[1000005];

int main()
{
    f>>N;
    for (int i = 1; i <= N; ++i)
        phi[i] = i-1;
    for (int i = 2; i <= N; ++i)
        for (int j = 2*i; j <= N; j += i)
            phi[j] -= phi[i];
    for(int i=2;i<=N;++i)
    {
        result+=phi[i];
    }
    g<<result*2+1;
    return 0;
}