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