#include <iostream>
#include <fstream>
#include <iomanip>
#include <algorithm>
#include <set>
#include <vector>
#include <map>
#include <queue>
#include <stack>
#include <utility>
#include <string>
#include <cstring>
#include <cctype>
#include <cmath>
#include <cstdio>
#include <cstdlib>
#include <limits>
#include <sstream>
#include <deque>
#include <bitset>
#include <complex>
#include <functional>
#include <memory>
#include <numeric>
#define x first
#define y second
typedef std::pair<int, int> pii;

using namespace std;
const int Max = 1000000;
int x[Max], S = 0, n;
int erat()
{
	for(int i = 0; i <= n; i++)
		x[i] = i;
	for(int i = 2; i <= n; i++)
	{
		if(x[i] == i)
		for(int j = i; j <= n; j += i)
		{
			x[j] /= i;
			x[j] *= (i-1);
		}
	}
	for(int i = 2; i <= n; i++)
		S += x[i];
}

int main () {
	ifstream fin("fractii.in");
	ofstream fout("fractii.out");
	fin >> n;
	fout << S * 2 + 1;
	return 0;
}