using System;

public class Program

{

    public static void Main()

    {

          string str = "hello"; 

          string str2 = "viral";  

          var ch = str.ToCharArray();

          var ch2 = str2.ToCharArray();

​

        for (int i = 0; i < ch.Length; i++) {

            for (int j = 0; j < ch2.Length; j++) {

                if (ch[i] == ch2[j]) {

                    ch2[j] = '\0';

                    ch2[j] = ch2[j + 1];

                }

​

            }

        }

​

        string s1cpy = ch.ToString();

        string s2cpy = ch2.ToString();

        Console.WriteLine(s1cpy);

    }

}