#pragma GCC optimize("Ofast")
#include <bits/stdc++.h>

typedef long long ll;

const ll mod=1e9+7;

const int dx[] = {0, 1, 0, -1};
const int dy[] = {1, 0, -1, 0};
const ll nmax=1000000;
#define all(x) x.begin(),x.end()
#define allr(x) x.rbegin(),x.rend()
#define rc(x)  return cout<<x<<"\n",0
#define sz(s)  (int) s.size()
#define pb push_back
#define mp make_pair
#define fr first
#define sc second
#define PI 3.14159265358979

using namespace std;

ll t,a[nmax];

int main() {
ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
	ifstream ("fractii.in");
	ofstream ("fractii.out");
	ll n;
	cin >> n;
	for (int i=2; i<=n; i++)a[i]=i-1; // nr de fractii posibile, in afara de cele cu rezultatul 1
	ll ans=0;
	for (int i=2; i<=n; i++) {
		ans+=a[i];
		for (int j=i+i; j<=n; j+=i) {
			a[j]-=a[i]; // pentru toti multiplii numarului i, scoatem din nr de fractii posibilie, nr de fractii echivalente
		}
	}
	ans=(ans*2)+1;
	cout << ans << '\n';
}