/**Zero 2**/
#include <iostream>
#include <fstream>
using namespace std;
ifstream fin("fractii.in");
ofstream fout("fractii.out");

int N, ff[1000002], rez;

int main(){
    fin>>N;
    for (int i=2; i<=N; i++)
        ff[i]=i-1;
    for(int i=2;i<=N; i++){
        rez+=ff[i];
        for(int t=i+i; t<=N; t+=i)
            ff[t]-=ff[i];

    }
    fout<<(1+2*rez);





    return 0;
}