#include <iostream>
#include <fstream>

using namespace std;

int main()
{
    fstream f("fractii.in",ios::in);
    fstream g("fractii.out",ios::out);
    long long int N,nr=0,i,j;
    f>>N;
    f.close();
    long long int phi[N+1]={};
    for(i=1;i<=N;i++)
        phi[i]=i-1;
    for(i=2;i<=N;i++){
        for(j=2*i;j<=N;j+=i){
            phi[j]-=phi[i];
        }
        nr+=phi[i];
    }
    g<<2*nr+1;
}