#include <iostream>
#define VM 1000001
#include <fstream>

using namespace std;

int x[VM];

typedef long long LL;

int main()
{
    ifstream f("fractii.in");
    ofstream g("fractii.out");
    LL n , s = 0;
    f>>n;
    for(int i = 1 ; i <= n ; ++i){
        x[i] = i - 1;
    }
    for(int i = 2 ; i <= n ; ++i){
        for(int j = 2 * i ; j <= n ; j += i){
            x[j] -= x[i];
        }
    }
    for(int i = 1 ; i <= n ; ++i){
        s += x[i] * 2;
    }
    g<<s + 1;
    return 0;
}