#include <fstream>
#include <iostream>
#include <stdint.h>

using namespace std;

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

fin >> n ;

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

for (long long i = 1 ; i <= n; ++i)
	sum += ar[i];

sum = 2 * sum + 1;

fou << sum << endl;

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