using System;

public class Program

{

    public static void Main()

    {

        string s1 = "abcnhrkfldnndfjur";

        Console.WriteLine(s1);

        Console.WriteLine();

        char ch1 = 'a';

        char ch2 = 'b';

        char ch3 = 'c';

        string s2 = "zzz";

        int IndexOfA = s1.IndexOf(ch1);

        int IndexOfB = s1.IndexOf(ch2);

        int IndexOfC = s1.IndexOf(ch3);

        if(IndexOfA == 0 && IndexOfB == 1 && IndexOfC == 2)

        {

            s1 = s1.Replace("abc", "www");

            Console.WriteLine(s1);

        }

        else

        {

                s1 = s1.Insert(s1.Length, s2);

                Console.WriteLine(s1);

        }

    }

}