#include <iostream>
#include <fstream>
#include <vector>
using namespace std;
int numere[1000005];
ofstream out("fractii.out");
long long ciurulluieratostene(int n)
{
	int i,fff;
	long long j,total=0;
	for (i = 2; i <= n; i++)
	{
		if (numere[i] == 0)
		{
			fff = n / i;
			for (j = i; j <= n; j += i)
			{
				if (numere[j] > 0){ numere[j]--; }
				numere[j] += fff;
			}
		}
		total += numere[i];
	}
	return total;
}
int main()
{
    ifstream in("fractii.in");
	int i,j,curent;
	long long raspuns,n;
	in >> n;
	raspuns=n*n-ciurulluieratostene(n);
	out << raspuns;
}