#include <fstream>
#include<iostream>
using namespace std;
ifstream fin("fractii.in");
ofstream fout("fractii.out");
int n,a[1000001],i,j,nr;
int main()
{
    fin>>n;
    for ( i = 1; i <= n; ++i)
    a[i] = i-1;
for ( i = 2; i <= n; i++)
    for ( j = 2*i; j <= n; j += i)
        a[j] -= a[i];
        nr=1;
for(i=2;i<=n;i++)
    nr=nr+(a[i]*2);
    fout<<nr;
}