#include <iostream>
#include <string>
#include <vector>
#include <algorithm>
#include <iomanip>
#include <utility>
#include <tuple>
#include <cmath>
#include <cstdint>
#include <cstdio>
#include <map>
#include <queue>
#include <set>
#include <stack>
#include <deque>
#include <unordered_map>
#include <unordered_set>
#include <bitset>
#include <cctype>
#include <cassert>
#include <functional>
#include <numeric>
#include <type_traits>
using namespace std;
#define ll long long
#define rep(i, n) for (int i = 0; i < (n); i++)
#define coutf(f) cout << fixed << setprecision(f)
#define all(v) (v).begin(), (v).end()
#define rall(v) (v).rbegin(), (v).rend()
const int inf = 1e9;
const ll INF = 1e18;
const int mod = 998244353;
using Graph = vector<vector<int>>;

int main() {
	int x;
	cin >> x;
	string s = "AABBABB";
	int ans = 0, now = 0;
	while (1) {
		rep(i, 7) {
			if (s[i] == 'A') {
				now += 2;
				ans += 2;
			}
			else {
				now--;
				ans++;
			}
			if (now == x) {
				cout << ans << endl;
				return 0;
			}
		}
	}
	return 0;
}