#include <iostream>
#include <fstream>
using namespace std;

int v[100000000];
int n;
long long c, solu=0;
int i;
int j;

int main()
{
    //cin >> n;
    ifstream f("fractii.in");
    f>>n;
    f.close();
    for (i=1; i<=n; i++)
    {
        v[i]=i-1;
    }

    for (i=2; i<=n; i++)
    {
        for (j=i+i; j<=n; j=j+i)
        {
            v[j]=v[j]-v[i];
        }
    }
    for (i=1; i<=n; i++)
    {
        c=v[i];
        solu=solu+c;


    }
    //cout << solu*2+1;
    ofstream g("fractii.out");
    g<<solu;
    g.close();
}