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 Rust (1.15.1) (judge verdict: Runtime Error)

use std::str::FromStr;
fn main(){
    
    let scan = std::io::stdin();
    let mut mode = String::new();
    let _ = scan.read_line(&mut mode);

    if mode == "1\n"{
        println!("Hello World!");
    }else if mode == "2\n"{
        let mut a_s = String::new();
        let _=scan.read_line(&mut a_s);
        let mut b_s = String::new();
        let _=scan.read_line(&mut b_s);
        let a = i32::from_str(&a_s).expect("");
        let b = i32::from_str(&b_s).expect("");
        println!("{}",a+b);
    }
}