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); } }