CsharpExperiment

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

//https://www.bilibili.com/video/BV1gR4y1b7oW?p=23&vd_source=724888e015829d762c2d6cf0b83d1657
class MainClass {
    static void Main() {
        int a = Convert.ToInt32(Console.ReadLine());
        Console.WriteLine("Hello World!" + a);
    }
}