Задача 4

using System;
using System.Collections.Generic;
namespace _5
{
    class Program
    {
        static char[] Row(char[] line, int beg, string model)
        {

            List<char> ans = new List<char>();
            for(int i=beg; i<line.Length; i++)
            {
                if (model.IndexOf(line[i]) == -1)
                {
                    ans.Add(line[i]);
                }
            }
            return ans.ToArray();
        }
        static void Main(string[] args)
        {

            Console.WriteLine(new String(Row("fjsingk".ToCharArray(),2,"ik")));
        }
    }
}