hdu1023：卡特兰数

import java.math.*;
import java.util.*;
public class Main 
{
    public static BigInteger BI(int x)
    {
        return BigInteger.valueOf(x);
    }
    public static BigInteger solve(BigInteger n)
    {
        BigInteger res;
        if(n.compareTo(BI(1))==0)
            res=BI(1);
        else
        {
            res=solve(n.add(BI(-1)));
            res=res.multiply(n.multiply(BI(4)).add(BI(-2)));
            res=res.divide(n.add(BI(1)));
        }
        return res;
    }
    public static void main(String[] args) 
    {
        Scanner in = new Scanner(System.in);
        while(in.hasNext())
        {
            BigInteger a=in.nextBigInteger();
            System.out.println(solve(a));
        }        
    }
}