#include <fstream>
#include <cmath>
#include <iostream>
long int x[1000001];
using namespace std;

int main()
{long int i,n,l=1,q;


ifstream a("fractii.in");
ofstream b("fractii.out");
a>>n;
a.close();
for(i=1;i<=n;i++){x[i]=i-1;} for(i=2;i<=n;i++){for(q=2*i;q<=n;q=q+i)x[q]=x[q]-x[i];}
for(i=1;i<=n;i++) l=l+2*x[i];


b<<l;
b.close();
    return 0;
}