using System;

​

public class Program

{

    public static void ChangeString(string val)

    {

        val = val.Replace("e", "@@@@@@@");  

        Console.WriteLine(val);

    }

    public static void Main()

    {

        string test = "Test";

        Console.WriteLine(test);

        ChangeString(test);

        Console.WriteLine(test);

    }

}