#include <iostream>
#include <fstream>
#include <math.h>
#define DIMMAX 1000000
using namespace std;
int v[DIMMAX];

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


int main()
{
    long long N, suma = 0;
    int i, j;
    fin>>N;
    for (i = 2; i <= N; i++)
        v[i] = i - 1;
    for (i = 2; i <= N; i++)
        for (j = 2 * i; j <= N; j += i)
            v[j] = v[j] - v[i];
    for (i = 1; i <= N; i++)
        suma += v[i];
    fout<<suma * 2 + 1;
    fin.close();
    fout.close();
    return 0;
}