#include <fstream>
#include <iostream>

using namespace std;

int main (){
int n;
int ar[1000001];
ifstream fin( "fractii.in", ios_base::in );
ofstream fou( "fractii.out", ios_base::out );

fin >> n ;

for (int i = 0 ; i <=n ; ++i){
	ar[i] = i - 1;
}
int sum = 0;
for (int j = 2; j <=n; ++j){
	for (int k = 2*j; k <=n; k+=j){
		ar[k] -= ar[j];
	}
	sum += ar[j];
}

sum = 2 * sum + 1;

fou << sum << endl;

fin.close();
fou.close();
return 0;
}