// jarda-L.cpp : This file contains the 'main' function. Program execution begins and ends there.
//
#include <iostream>
#include <queue>
#define ll long long
using namespace std;
ll n;
int main()
{
cin >> n;
vector<ll>dp(n + 1, 0);
dp[0] = 1;
dp[1] = 1;
dp[2] = 2;
dp[3] = 5;
if (n <= 3)
{
cout << dp[n];
return 0;
}
for (int i = 4; i <= n; ++i)
{
dp[i] = dp[i - 1] + dp[i - 2];
int j = i - 3;
while (j>=0)
{
dp[i] += 2 * dp[j];
--j;
}
}
//for (auto& e : dp)cout << e << " ";
cout << dp[n];
return 0;
}
// Run program: Ctrl + F5 or Debug > Start Without Debugging menu
// Debug program: F5 or Debug > Start Debugging menu
// Tips for Getting Started:
// 1. Use the Solution Explorer window to add/manage files
// 2. Use the Team Explorer window to connect to source control
// 3. Use the Output window to see build output and other messages
// 4. Use the Error List window to view errors
// 5. Go to Project > Add New Item to create new code files, or Project > Add Existing Item to add existing code files to the project
// 6. In the future, to open this project again, go to File > Open > Project and select the .sln file