#include <iostream>
#include <fstream>

using namespace std;

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

const int NMAX = 1000000;
long long x[NMAX];

int main()
{
    int n;
    long long nr=0;
    fin>>n;
    for(int i=2;i<=n;i++)
    {
        x[i]+=i-1;
        for(int j=2*i;j<=n;j+=i)
        {
            x[j]-=x[i];
        }
        nr+=x[i];
    }
    fout<<2*nr+1<<endl;
    return 0;
}