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

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 ;

memset(ar, 0, sizeof(long long)* 1000001);
long long sum = 0;
for (long long j = 2; j <=n; ++j){
	ar[j] += j - 1;
	for (long long 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;
}