#include <iostream>
#include <fstream>

using namespace std;

long long phi(long long n) {
	long long result = n;
	for (long long i=2; i*i<=n; ++i)
		if (n % i == 0) {
			while (n % i == 0)
				n /= i;
			result -= result / i;
		}
	if (n > 1)
		result -= result / n;
	return result;
}
long long n,answer;
int main()
{
    ifstream fin("fractii.in");
    cin>>n;
    answer=1;
    for(long long i=2;i<=n;i++){
        answer+=2*phi(i);
    }
    ofstream fout("fractii.out");
    cout << answer ;
    return 0;
}