import java.io.File;
import java.io.FileNotFoundException;
import java.io.PrintStream;
import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;

public class Main {

    public static void main(String[] args) throws FileNotFoundException {
        
        File file = new File("fractii.in");
        Scanner input = new Scanner (file);
        PrintStream fileStream = new PrintStream("fractii.out");
        System.setOut(fileStream);
        
        long N = input.nextInt();
        System.out.println(indicatorulLuiEuler(N));
        
    }
    
    public static long indicatorulLuiEuler(long N){
        List<Long> vector = new ArrayList<>();
        long sum=0;
        vector.add((long)0);
        for (long i=1;i<=N;++i)
            vector.add(i-1);
        for (int i = 2; i <= N; ++i)
            for (int j = 2*i; j <= N; j += i)
                vector.set(j, vector.get(j)-vector.get(i));
        for (int i=1;i<=N;i++)
            sum+=vector.get(i);
        return sum*2+1;
    }
    
}