#include <iostream>
#define dim 1000001
#include <fstream>
using namespace std;


ifstream f("fractii.in");
ofstream of("fractii.out");


int phi[dim];

int main()
{
   long long int n, i, j, cnt = 0;
    f >> n;

    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];

    for(i = 2; i <= n; i++)
            cnt += phi[i];
        cnt = cnt * 2 + 1 ;

    of << cnt;

    return 0;
}