#include "bits/stdc++.h"
//#define int long long
using namespace std;
using ll = long long;
using P = pair<ll, ll>;
const ll INF = (1LL << 61);
ll mod = 1000000007;

signed main() {
	ios::sync_with_stdio(false);
	cin.tie(0);
	ll N; cin >> N;
	if (N == 1)cout << 1 << endl;
	else if (N == 2)cout << 2 << endl;
	else if (N == 3)cout << 3 << endl;
	else {
		ll now = 7;
		now += (N - 4) * 5;
		now++;
		cout << now << endl;
	}
	return 0;
}