using System;

​

public static class MathUtils

{

    public static int Factorial(uint n)

    {

        int factorial=1;

        for(int i=2;i<=n;i++)

        {

            factorial*=i;

        }

        return factorial;

    }

}

​

public static class CatalanNumbers

{

    private static int CalculateDivisor(uint n)

    {

        return (MathUtils.Factorial(n+1)*(MathUtils.Factorial(n)));

    }

    private static int CalculateDividend(uint n)

    {

        return (MathUtils.Factorial(2*n));

    }

    public static int Calculate(uint n)

    {

        return CalculateDividend(n)/CalculateDivisor(n);

    }

}

public class Program

{

    public static void Main()

    {

        Console.WriteLine(CatalanNumbers.Calculate(2));

    }

}