#include <iostream>
#include <fstream>
#define NMAx 1000001
using namespace std;
ifstream f("fractii.in");
ofstream g("fractii.out");
long long s=1;
int i,j,ired[NMAx],N;
int main()
{
    f>>N;
    for(i=2;i<=N;i++)
        ired[i]=i-1;

    for(i=2;i<=N;i++)
        for(j=2*i;j<=N;j=j+i)
        ired[j]-=ired[i];

    for(i=2;i<=N;i++)
        s+=ired[i];
    g<<2*s-1;
    return 0;
}