using System;

using System.Linq;

public class Program

{

    public static void Main()

    {

        var q = new StringQueue("abcdefghij");

​

        Console.WriteLine(q.Next(3));

        Console.WriteLine(q.Next(3));

        Console.WriteLine(q.Next(3));

        Console.WriteLine(q.Next(3));

        Console.WriteLine(q.Next(3));

    }

}

​

public class StringQueue

{

    private readonly string original;

    private int index;

​

    public StringQueue(string data)

    {

        this.original = data;

        this.index = 0;

    }

    public string Next(int count)

    {

        var chars = original.Skip(this.index).Take(count).ToArray();

        this.index += count;

        return new string(chars);

    }

}