#include<iostream>
#include<algorithm>
using namespace std;
using lint=int64_t;

int N;
int N2;
int ans=0;
int ocnt;
int ccnt;

void dfs(int d)
{
	if(ocnt>N || ccnt>N)
		return;
	if(ccnt>ocnt)
		return;
	
	if(d==N2)
	{
		ans++;
		return;
	}

	ocnt++;
	dfs(d+1);
	ocnt--;
	ccnt++;
	dfs(d+1);
	ccnt--;
	return;
}

int main()
{
	cin >> N;
	N2=2*N;
	dfs(0);
	cout << ans << endl;
	return 0;
}