#include <iostream>
#include <fstream>
using namespace std;
int n,e[1000000],suma=1;
int main()
{
    ifstream fin("fractii.in");
    ofstream fout("fractii.out");
    fin >>n;
    for(int i=1;i<=n;i++)
        e[i]=i-1;
    for(int i=2;i<=n;i++){suma+=e[i];
        for(int j=2*i;j<=n;j+=i)
            e[j]-=e[i];
    }
    fout<<suma*2-1;






    return 0;
}