tupoe_govno

#define _CRT_SECURE_NO_WARNINGS
#include <iostream>
#include <cstdio>
#include <vector>
#include <cmath>
#include <string>
#include <algorithm>
#include <string>
#include <deque>
#include <iomanip>
#include <cstddef>

#define F first
#define S second

using namespace std;


const long double eps = 0.000000005;
const long double pi = 3.1415926535897932;
const long long inf = 1e9;

deque<int> a;

int main()
{
    ios_base::sync_with_stdio(0);
    //freopen("input.txt", "r", stdin);freopen("output.txt", "w", stdout);
    // freopen("slalom.in", "r", stdin);freopen("slalom.out", "w", stdout);

    int n;
    cin >> n;

    for (int i = 0; i < n; i++)
        a.push_back(1);

    int ans = 0;

    while (a.size() > 1)
    {
        if (a.front() == 1)
        {
            a.pop_front();
            a.pop_front();
            a.push_back(2);
            a.push_back(3);
        }
        else
            if (a.front() == 2)
            {
                a.pop_front();
                a.pop_front();
                a.push_back(1);
            }
            else
            {
                a.pop_front();
                a.pop_front();
                a.push_back(1);
                a.push_back(1);
                a.push_back(1);
            }
        ans++;
    }

    cout << ans

    return 0;
}