// Craciun Catalin
//  Fractii
//   www.infoarena.ro/problema/fractii
#include <fstream>
#include <iostream>

#define NMax 100005

using namespace std;

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

long n;
long A[NMax];

void solve()
{
	long s=0;

	for (long i=1;i<=n;i++)
		A[i]=i;

	for (long i=2;i<=n;i++)
	{
		s+=A[i];
		for (long j=2*i; j<=n;j+=i)
			A[j]-=A[i];
	}

	g<<s<<'\n';
}

int main()
{
	f>>n;
	f.close();

	solve();

	return 0;
}