using System;

using System.Text;

public class Program

{

    public static void Main()

    {

        StringBuilder sb = new StringBuilder("Hello world!");

        sb.Append("foo bar");

        Console.WriteLine(sb);

        sb.AppendFormat("{0:c}", 1234);

        Console.WriteLine(sb);

        sb.Insert(6, "beautiful");

        Console.WriteLine(sb);

        sb.Remove(0, 5);

        Console.WriteLine(sb);

        sb.Replace("!", "#"); 

        Console.WriteLine(sb);

    }

}