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 Java8 (OpenJDK 1.8.0) (judge verdict: Accepted)

import java.io.BufferedReader;
import java.io.Closeable;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.util.Set;
import java.util.HashSet;

public class Main {

    public static void main(String[] args) throws IOException {
        try (InputReader reader = new InputReader(System.in)) {
            solve(reader);
        }
    }

    private static void solve(InputReader reader) throws IOException {
        int age = reader.readInt();
        if (age == 1) {
            System.out.println("Hello World");
        } else {
            int a = reader.readInt();
            int b = reader.readInt();
            System.out.println(a + b);
        }
    }
}

class Util {
    static int gcd(int m, int n) {
        int min = Math.min(m, n);
        int max = Math.max(m, n);
        while (min != 0) {
            int tmp = min;
            min = max % tmp;
            max = tmp;
        }

        return max;
    }

    static int lcm(int m, int n) {
        return m / gcd(m, n) * n;
    }
}

class InputReader implements Closeable, AutoCloseable {
    private final BufferedReader br;

    InputReader(InputStream inputStream) {
        this.br = new BufferedReader(new InputStreamReader(inputStream));
    }

    String readLine() throws IOException {
        return this.br.readLine();
    }

    int readInt() throws IOException {
        return Integer.parseInt(this.readLine());
    }

    long readLong() throws IOException {
        return Long.parseLong(this.readLine());
    }

    double readDouble() throws IOException {
        return Double.parseDouble(this.readLine());
    }

    String[] readStringsSplitByDelimiter(String delimiter) throws IOException {
        return this.readLine().split(delimiter);
    }

    int[] readIntsSplitByDelimiter(String delimiter) throws IOException {
        String[] strings = this.readStringsSplitByDelimiter(delimiter);

        int stringsLength = strings.length;
        int[] ints = new int[stringsLength];
        for (int i = 0; i < stringsLength; i++) {
            ints[i] = Integer.parseInt(strings[i]);
        }

        return ints;
    }

    long[] readLongsSplitByDelimiter(String delimiter) throws IOException {
        String[] strings = this.readStringsSplitByDelimiter(delimiter);

        int stringsLength = strings.length;
        long[] longs = new long[stringsLength];
        for (int i = 0; i < stringsLength; i++) {
            longs[i] = Long.parseLong(strings[i]);
        }

        return longs;
    }

    double[] readDoublesSplitByDelimiter(String delimiter) throws IOException {
        String[] strings = this.readStringsSplitByDelimiter(delimiter);

        int stringsLength = strings.length;
        double[] doubles = new double[stringsLength];
        for (int i = 0; i < stringsLength; i++) {
            doubles[i] = Double.parseDouble(strings[i]);
        }

        return doubles;
    }

    @Override
    public void close() throws IOException {
        this.br.close();
    }
}