#include "bits/stdc++.h"

using namespace std;

void solve(void)
{
	int n;
	cin >> n;
	int ans = 0;
	for (int i = 0; i < (1<<(n*2)); i++)
	{
		if (__builtin_popcount(i) != n) continue;
		int cnt = 0, ok = 1;
		for (int j = 0; j < 2*n; j++)
		{
			if (i >> j & 1)
			{
				cnt++;
			}
			else
			{
				if  (cnt == 0)
				{
					ok = 0;
					break;
				}
				cnt--;
			}
		}
		ans += ok;
	}
	cout << ans << endl;

}

int main()
{
	solve();
	//cout << "yui(*-v・)yui" << endl;
	return 0;
}