using System;

using System.Collections.Generic;

​

public class FairRandom {

    private int lastNumber = 3;   // we always need to know the last number generated

                                  // so it's a private field

    private Random rnd;

    public FairRandom(int seed){

        rnd = new Random(seed);

    }

                                  // we would also like to reuse the same Random object 

    public int Next() {

        int num;

        if (lastNumber == 6) {

            num = rnd.Next(1,3);

        }

        else if (lastNumber == 1) {

            num = rnd.Next(5,7);

        }

        else {

            num = rnd.Next(1,7); 

        }

        lastNumber = num;

        return num;

    }

}

​

public class Program

{

    public static void Main()

    {

        FairRandom rnd = new FairRandom(90);

        for (int i=0;i<100;i++)

            Console.WriteLine(rnd.Next());

    }

}