HDU1502 Regular Words

import java.math.BigInteger;
import java.util.Scanner;
public class Main{
    
    public static void main(String[] args){
        Scanner cin =new Scanner(System.in);
        BigInteger dp[][][] = new BigInteger[61][61][61];
        dp[0][0][0] = BigInteger.ZERO;
        for(int i = 0; i < 2;  i++){
            for(int j = 0; j <= i; j++){
                for(int k = 0; k <= j; k++){
                    dp[i][j][k] = BigInteger.ONE;
        }
        }
        }
        
        int n;
        while(cin.hasNext()){
            n = cin.nextInt();
            for(int i = 2; i <= n ; i++){
                for(int j = 0; j <=i; j++){
                    for(int k = 0; k <= j; k++){
                        dp[i][j][k] = BigInteger.ZERO;
                        if(i - 1 >= j){
                            dp[i][j][k] = dp[i][j][k].add(dp[i -  1][j][k]);
                        }
                        if(j - 1 >= k){
                            dp[i][j][k] = dp[i][j][k].add(dp[i][j - 1][k]);
                        }
                        if(k - 1 >= 0){
                            dp[i][j][k] = dp[i][j][k].add(dp[i][j][k - 1]);
                        }
                    }
                }
            }
            System.out.println(dp[n][n][n]);
            System.out.println();
        }
    }
}