#include<iostream>
#include <fstream>
using namespace std;
ifstream fin("fractii.in");
ofstream fout("fractii.out");
int main(){
    int N,counter=0;
    fin>>N;
    fin.close();
    int arr[N];
    for (int i = 1; i <= N; ++i)
        arr[i] = i - 1;
    for (int i = 2; i <= N; ++i)
        for (int j = 2 * i; j <= N; j += i)
            arr[j] -= arr[i];
    for (int i = 2; i <= N; ++i)
        counter += arr[i];
    fout<<2 * counter + 1;
    fout.close();
    return 0;
}