using System;

using System.Collections.Generic;

public class Program

{

    public static void Main()

    {

        Opdr3RandomNumbers(100, 100, 1);

        Opdr3RandomNumbers(1, 100, 4);

        Console.WriteLine("Done");

    }

    public static Stack<int> Opdr3RandomNumbers(int lower, int upper, int count)

    {

        Stack<int> stack = new Stack<int>();

        HashSet<int> occurredNumbers = new HashSet<int>();

​

        Random randomNumber = new Random();

​

        while (stack.Count < count)

        {

            int number = randomNumber.Next(lower, upper);

            bool hasOccurred = occurredNumbers.Contains(number);

​

            while (hasOccurred) {

                number = randomNumber.Next(lower, upper);

                hasOccurred = occurredNumbers.Contains(number);

            }

​

            stack.Push(number);

            occurredNumbers.Add(number);

        }

​

        return stack;

    }

}