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

unsigned long int n;
unsigned long long int s = 0;
unsigned long int k;
unsigned int fractii[1000001];

int main()
{
	ifstream fin("fractii.in");
	ofstream fout("fractii.out");
	fin >> n;
	for(unsigned long int i=1; i<=n; i++)
	{
		fractii[i] = n;
	}
	for (unsigned long int i=2; i<=n; i++)
	{
		fractii[i]--;
		k = i+i;
		while (k <= n)
		{
			fractii[k] -= 2;
			k = k + i;
		}
	}
	for(unsigned long int i=1; i<=n; i++)
		s += fractii[i];
	fout << s;
	fin.close();
	fout.close();
	return 0;
}