using System;

public class Program {

  public static void Main() {

​

    string str1 = "study \"C#\" using a great course!";

    Console.WriteLine(str1);

​

    string str2 = "study \'C#\' using a great course!";

    Console.WriteLine(str2);

​

    string str3 = "study C#\\CSharp using a great course!";

    Console.WriteLine(str3);

  }

}