#include <iostream>
#include <fstream>
using namespace std;
ifstream f("fractii.in");
ofstream g("fractii.out");

int euler[1000005],n;
long long s;

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