#include <iostream>
#include <vector>
#include <algorithm>

using namespace std;

typedef long long LL;

int main(void) {
	std::ios::sync_with_stdio(false);
	std::cin.tie(0);
	int N;
	cin >> N;
	LL** dp;
	dp = (LL**)calloc(N+1, sizeof(LL));
	for (int i = 0; i < N+1; i++) {
		dp[i] = (LL*)calloc(N+1, sizeof(LL));
	}
	dp[0][0] = 1;
	for (int i = 0; i < N+1; i++) {
		for (int j = 0; j < N+1; j++) {
			if (i * 2 + j > N) {
				break;
			}
			if ((i > 0) && (j > 0)) {
				dp[i][j] = dp[i - 1][j] + dp[i][j - 1];
			} else if (i > 0) {
				dp[i][j] = dp[i - 1][j];
			} else if (j > 0) {
				dp[i][j] = dp[i][j - 1];
			}
		}
	}
	LL count = 0;
	int piv = N;
	for (int i = 0; i < N + 1; i++) {
		if (piv < 0) {
			break;
		}
		count += dp[i][piv];
		piv -= 2;
	}
	cout << count << endl;
}