#include <cstdio>

#include <cstring>

const int maxn = 105, mod = 10000;

int n;

struct gao {

	int data[100], wei;

	gao(void) {

		memset(data, 0, sizeof data);

		wei = 0;

	}

	gao operator+(int aa) const {

		gao rt;

		rt.data[0] = aa;

		for (int i = 0; i < wei; ++i) {

			rt.data[i] += data[i];

			if (rt.data[i] >= mod) {

				rt.data[i] -= mod;

				++rt.data[i + 1];

			}

		}

		rt.wei = wei + (rt.data[wei]? 1: 0);

		return rt;

	}

	gao operator-(const gao & rhs) const {

		gao rt;

		for (int i = 0; i < wei; ++i) {

			rt.data[i] += data[i] - rhs.data[i];

			if (rt.data[i] < 0) {

				rt.data[i] += mod;

				--rt.data[i + 1];

			}

		}

		rt.wei = wei;

		while (rt.wei > 0 && !rt.data[rt.wei - 1]) {

			--rt.wei;

		}

		return rt;

	}

	gao operator*(int aa) const {

		gao rt;

		for (int i = 0; i < wei; ++i) {

			rt.data[i] += data[i] * aa;

			rt.data[i + 1] += rt.data[i] / mod;

			rt.data[i] %= mod;

		}

		rt.wei = wei + (rt.data[wei]? 1: 0);

		return rt;

	}

	void print(void) {

		printf("%d", data[wei - 1]);

		for (int i = wei - 2; i >= 0; --i) {

			printf("%04d", data[i]);

		}

	}

} f[maxn];

int main(void) {

	f[1].data[0] = 1;

	f[1].wei = 1;

	f[2].data[0] = 5;

	f[2].wei = 1;

	scanf("%d", &n);

	for (int i = 3; i <= n; ++i) {

		f[i] = f[i - 1] * 3 - f[i - 2] + 2;

	}

	f[n].print();

	puts("");

	return 0;

}