Problem:
﻿Score: 100 points

Problem Statement

In 2020, AtCoder Inc. with an annual sales of more than one billion yen (the currency of Japan) has started a business in programming education.

One day, there was an exam where a one-year-old child must write a program that prints Hello World, and a two-year-old child must write a program that receives integers A, B and prints A+B.

Takahashi, who is taking this exam, suddenly forgets his age.

He decides to write a program that first receives his age N (1 or 2) as input, then prints Hello World if N=1, and additionally receives integers A, B and prints A+B if N=2.

Write this program for him.

Constraints

N is 1 or 2.

A is an integer between 1 and 9 (inclusive).

B is an integer between 1 and 9 (inclusive).

Input

Input is given from Standard Input in one of the following formats:

1

2
A
B

Output

If N=1, print Hello World; if N=2, print A+B.

Sample Input 1

1

Sample Output 1

Hello World

As N=1, Takahashi is one year old. Thus, we should print Hello World.

Sample Input 2

2
3
5

Sample Output 2

8

As N=2, Takahashi is two years old. Thus, we should print A+B, which is 8 since A=3 and B=5.

Solution in C# (Mono 4.6.2.0) (judge verdict: Accepted)

using System;
class Program
    {
        static void Main(string[] args)
        {
            int age;
            int a;
            int b;
            if (int.TryParse(Console.ReadLine(), out age))
            {
                if(age == 1)
                {
                    Console.WriteLine("Hello World");
                }
                else if(age == 2)
                {
                    var A = Console.ReadLine();
                    var B = Console.ReadLine();

                    if(int.TryParse(A,out a) && int.TryParse(B,out b))
                    {
                        if(a > 0 && a < 10 && b > 0 && b < 10)
                        {
                            Console.WriteLine(a + b);
                        }
                    }
                }
            }          
        }
    }