#include <bits/stdc++.h>
using namespace std;

int main()
{
	int n;
	cin >> n;

	n *= 2;

	int dp[n + 1][n + 1]{};
	dp[0][0] = 1;

	for (int i = 0; i < n; i++)
	{
		for (int j = 0; j <= n; j++)
		{
			if (0 <= j - 1)
			{
				dp[i + 1][j - 1] += dp[i][j];
			}
			if (j + 1 <= n)
			{
				dp[i + 1][j + 1] += dp[i][j];
			}
		}
	}

	cout << dp[n][0] << endl;

	return 0;
}