#include <iostream>
#include <fstream>
#define N 1000010

using namespace std;

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

int phi[N],i,j,n,k;
long long x=0;
int main()
{
    f>>n;
    for(i=1;i<=n;i++)
        phi[i]=i-1;
    for(i=2;i<=n;i++)
    {
        for(j=i+i;j<=n;j=j+i)
        {
            phi[j]=phi[j]-phi[i];
        }
        x=x+phi[i];
    }
    g<<2*x+1;
}