#include "pch.h"
#include <iostream>
#include <algorithm>
using namespace std;

int N, tmpDb = 0, best = 0, startRequest = 1;
int Method1(int, int);
int Method2(int, int);

int main()
{
    cin >> N;

    int best = 0;
    for (int i = 0; i < 4; i++)
    {
        startRequest = i;
        best = max(Method1(N, i), best);
        if ((N + i) % 3 == 0 && i != 0) break;
    };
    cout << best << endl;
}

int Method1(int full, int empty)
{
    tmpDb += full;
    //cout << "full: " << full << endl;
    empty += full;
    //cout << "empty: " << empty << endl;
    if (empty >= startRequest && full < 3)
    {
        int toReturn = tmpDb;
        tmpDb = 0;
        return toReturn;
    }
    return Method1(empty / 3, full / 3);
}

int Method2(int full, int empty)
{
    tmpDb += full;
    //cout << "full: " << full << endl;
    empty += full;
    //cout << "empty: " << empty << endl;
    if (empty >= startRequest && full < 3)
    {
        int toReturn = tmpDb;
        tmpDb = 0;
        return toReturn;
    }
    return Method2(empty / 3, (empty / 3) % 3);
}