#include <cstdlib>
#include <cstdio>
#include <iostream>
#include <fstream>

using namespace std;

int main()
{
	int n;
	FILE *f = fopen("fractii.in","r");
	fscanf(f,"%d",&n);
	fclose(f);
	long long nr = 0;
	int vector[100000];
	
	for(int i=2;i<=n;i++)
		vector[i]=i-1; 
	for(int i=2;i<=n;i++){ 
		nr=nr+vector[i];
		for(int j=2*i;j<=n;j+=i) 
			vector[j]-=vector[i]; 
	} 

	ofstream out; 
	out.open("fractii.out");
	out << (long long) nr*2+1;
	out.close();
	return 0;
}