#include <iostream>
#include <fstream>
 
using namespace std;
 
ifstream f("fractii.in");
ofstream g("fractii.out");
 
int ciur[1000001];
int n;
long long int fractii = 0;
 
int main()
{
    f >> n;
    for(int i = 1 ; i <= n ; i++){
        ciur[i] = i;
    }
 
    for(int i = 1 ; i <= n ; i++){
        fractii += ciur[i];
        for(int j = i*2 ; j <= n ; j += i)
            ciur[j] -= ciur[i];
    }
    g << 2*fractii-1;
 
 
    return 0;
}