#include <bits/stdc++.h>

using namespace std;

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

unsigned int phi[1000002];
int n;
int s;

int main()
{
    int i, j;
    fin>>n;
    for(i=1; i<=n; i++)
        phi[i]=i-1;
    for(i=2; i<=n; i++)
        for(j=i*2; j<=n; j+=i)
            phi[j]-=phi[i];
    for(i=1; i<=n; i++)
        s+=2*phi[i];   ///p/q ired => q/p ired
    s+=1;  ///adaugam 1/1
    fout<<s<<'\n';
    return 0;
}