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;
using System.Collections.Generic;
using System.Linq;
using System.Text;

using static System.Console;
using static PB10004.Algorithm.Util;

namespace PB10004.Algorithm
{
    class Template
    {
        static void Main(string[] args)
        {
            new A().Solve();
        }
    }
    class A
    {
        public void Solve()
        {
            var N = ReadInt();
            if(N == 1)
            {
                WriteLine("Hello World");
            }
            else
            {
                WriteLine(ReadInt() + ReadInt());
            }
        }
    }
    class B
    {
        public void Solve()
        {

        }
    }
    class C
    {
        public void Solve()
        {
        }
    }
    class D
    {
        public void Solve()
        {
        }
    }
    public static class Util
    {
        /// <summary>
        /// 標準入力をint型にパースする
        /// </summary>
        /// <returns></returns>
        public static int ReadInt()
        {
            return int.Parse(ReadLine());
        }
        /// <summary>
        /// 標準入力をint型の配列にする
        /// </summary>
        /// <returns></returns>
        public static int[] ReadIntArray()
        {
            return ReadLine().Split(' ').Select(x => int.Parse(x)).ToArray();
        }
        /// <summary>
        /// 標準入力をlong型にパースする
        /// </summary>
        /// <returns></returns>
        public static long ReadLong()
        {
            return long.Parse(ReadLine());
        }
        /// <summary>
        /// 標準入力をlong型の配列にする
        /// </summary>
        /// <returns></returns>
        public static long[] ReadLongArray()
        {
            return ReadLine().Split(' ').Select(long.Parse).ToArray();
        }
        /// <summary>
        /// 一定値の数列を生成する
        /// </summary>
        /// <param name="value"></param>
        /// <param name="length"></param>
        /// <returns></returns>
        public static IEnumerable<long> ConstSeq(long value, long length)
        {
            for (int i = 0; i < length; i++)
            {
                yield return value;
            }
        }
        /// <summary>
        /// int配列の累積和を求める
        /// </summary>
        /// <param name="array"></param>
        /// <returns></returns>
        public static IEnumerable<int> CumulativeSum(IEnumerable<int> array)
        {
            int tmp = 0;
            foreach (var num in array)
                yield return tmp += num;
        }
        /// <summary>
        /// long配列の累積和を求める
        /// </summary>
        /// <param name="array"></param>
        /// <returns></returns>
        public static IEnumerable<long> CumulativeSum(IEnumerable<long> array)
        {
            long tmp = 0;
            yield return tmp;
            foreach (var num in array)
                yield return tmp += num;
        }
        /// <summary>
        /// 最大公約数をユークリッドの互除法で求める
        /// </summary>
        /// <param name="a"></param>
        /// <param name="b"></param>
        /// <returns></returns>
        public static long Gcd(long a, long b)
        {
            return b == 0 ? a : Gcd(b, a % b);
        }
        /// <summary>
        /// 最小公倍数を求める
        /// </summary>
        /// <param name="a"></param>
        /// <param name="b"></param>
        /// <returns></returns>
        public static long Lcm(long a, long b)
        {
            return a * b / Gcd(a, b);
        }
    }
}