C++ :

#include <iostream> 
using namespace std;

typedef long long LongLong;

int main()
{
	LongLong data[31] = { 0 };

	data[0] = 1;
	data[1] = 1; 
	//cout << "fdsfds" << endl;
	for (int i = 2; i <= 30; i++)
	{
		data[i] = 0;
		for (int j = 0; j < i; j++)
			data[i] += data[j] * data[i - j - 1];
	}
	/*for (int k = 0; k <= 30; k++)
	{
		cout << data[k] << endl;
	}*/
	int n;
	while (cin >> n)
	{
		cout << data[n] << endl;
	}

	return 0;
}