#include <iostream>
#include <array>

constexpr int N = 28;

constexpr std::array<int, N + 1> jarda() {
    std::array<int, N + 1> j{ 1, 1 };

    int h = 0;
    for (int i = 2; i <= N; i++) {
        j[i] = j[i - 2] + j[i - 1] + h;
        h += 2 * j[i - 2];
    }

    return j;
}

static constexpr auto j = jarda();

int main() {
    int n;
    std::cin >> n;
    std::cout << j[n] << std::endl;

    return 0;
}