#include <bits/stdc++.h>

using namespace std;

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

int n,*p;
long long int nr = 0;

int main()
{
    in>>n;
    in.close();
    p = new int[n+1];
    //
    for(int i=1;i<=n;i++)
        p[i] = i-1;
    for(int i=2;i<=n;i++)
        for(int j=2*i;j<=n;j+=i)
        p[j] -= p[i];
    for(int i=1;i<=n;i++)
        nr+=p[i];
       out<<nr*2+1<<'\n';
    //
    delete[] p;
}